示例#1
0
        public static void Initial(
            ref AngularMesh[] amesh,
            ref SpatialMesh[] smesh,
            ref double[][][][] flux,
            ref double[][][][] d,
            ref double[][][][] RHS,
            ref double[][][][] q,
            ref int[][] noflevel,
            ref BoundaryCoupling[] b,
            int level,
            int mgMethod,
            int vacuum,
            double nTissue,
            double nExt,
            int aMeshLevel,
            int aMeshLevel0,
            int sMeshLevel,
            int sMeshLevel0,
            double[][][] ua,
            double[][][] us,
            MultiGridCycle Mgrid)
        {
            //Purpose: in this function, we load the following four ".txt" files:
            //             1) "amesh.txt": "ns", "a" and "w" for angular mesh
            //             3) "ua.txt": absorption coefficient
            //             4) "us.txt": scattering coefficient

            //         we first load the mesh files:
            //             1.1. "amesh.txt": "ns", "a" and "w" for angular mesh

            //         and then we compute the following for spatial mesh:
            //             2.1. "smap", "cf" and "fc"

            //         and finally malloc the following for multigrid algorithm:
            //             3.1. "noflevel"
            //             3.2. "ua", "us", "flux", "RHS", "d" and "q"
            //             3.3.  "b"

            int    tempsize = 20, tempsize2 = 20;
            int    i, j, k, m, n, nt, np, ne, ns, da = aMeshLevel - aMeshLevel0, ds = sMeshLevel - sMeshLevel0;
            double x1, x2, x3, y1, y2, y3;

            int[][]    t;
            int[][]    e;
            int[][]    p2;
            int[][]    smap;
            double[][] p;


            // 2.1. compute "c", "ec", "a" and "p2"
            //      p2[np][p2[np][0]+1]: triangles adjacent to one node
            //      For the 2nd index, the 1st element is the total number of triangles adjacent to this node,
            //      the corresponding triangles are saved from the 2nd.
            //      Example:    assume triangles [5 16 28 67] are adjacent to the node 10, then
            //                  p2[10][0]=4, p2[10][1]=5, p2[10][2]=16, p2[10][3]=28 and p2[10][4]=67.
            for (i = 0; i <= sMeshLevel; i++)
            {
                p = smesh[i].P; t = smesh[i].T; nt = smesh[i].Nt; np = smesh[i].Np; e = smesh[i].E; ne = smesh[i].Ne;

                smesh[i].C = new double[nt][];
                for (j = 0; j < nt; j++)
                {
                    smesh[i].C[j] = new double[2];
                    for (k = 0; k < 2; k++)
                    {
                        smesh[i].C[j][k] = (p[t[j][0]][k] + p[t[j][1]][k] + p[t[j][2]][k]) / 3;
                    }// center of triangle
                }

                smesh[i].Ec = new double[ne][];
                for (j = 0; j < ne; j++)
                {
                    smesh[i].Ec[j] = new double[2];;
                    for (k = 0; k < 2; k++)
                    {
                        smesh[i].Ec[j][k] = (p[e[j][1]][k] + p[e[j][2]][k]) / 2;
                    }                                                           // center of edge
                }

                smesh[i].A = new double[nt];;
                for (j = 0; j < nt; j++)
                {
                    x1            = p[t[j][0]][0]; y1 = p[t[j][0]][1];
                    x2            = p[t[j][1]][0]; y2 = p[t[j][1]][1];
                    x3            = p[t[j][2]][0]; y3 = p[t[j][2]][1];
                    smesh[i].A[j] = MathFunctions.Area(x1, y1, x2, y2, x3, y3);//area of triangle
                }

                p2 = new int[np][];
                for (j = 0; j < np; j++)
                {
                    p2[j] = new int[tempsize];
                    // tempsize is the initial length of the second index of "p2", and it may cause problem if it is too small.
                    p2[j][0] = 0;
                    for (k = 1; k < tempsize; k++)
                    {
                        p2[j][k] = -1;
                    }
                }

                for (j = 0; j < nt; j++)
                {
                    for (k = 0; k < 3; k++)
                    {
                        p2[t[j][k]][0] += 1;
                        p2[t[j][k]][p2[t[j][k]][0]] = j;
                    }
                }

                for (j = 0; j < np; j++)
                {
                    if (p2[j][0] + 1 > tempsize)
                    {
                        Console.WriteLine("WARNING: tempsize for p2 is too small!!\n");
                        goto stop;
                    }
                }

                smesh[i].P2 = new int[np][];
                for (j = 0; j < np; j++)
                {
                    smesh[i].P2[j] = new int[(p2[j][0] + 1)];
                    for (k = 0; k <= p2[j][0]; k++)
                    {
                        smesh[i].P2[j][k] = p2[j][k];
                    }
                }
            }

            // 2.2. compute "smap", "cf" and "fc"
            //      For the data structure of "smap", see "spatialmapping";
            //      For the data structure of "cf" and "fc", see "spatialmapping2".
            //      Note: those arrays are not defined on the coarsest spatial mesh (i=0),
            //      since they are always saved on the fine level instead of the coarse level.
            for (i = 1; i <= sMeshLevel; i++)
            {
                smap = new int[smesh[i - 1].Nt][];
                for (j = 0; j < smesh[i - 1].Nt; j++)
                {
                    smap[j] = new int[tempsize2];
                    // tempsize2 is the initial length of the second index of "smap", and it may cause problem if it is too small.
                    smap[j][0] = 0;
                    for (k = 1; k < tempsize2; k++)
                    {
                        smap[j][k] = -1;
                    }
                }
                Mgrid.SpatialMapping(smesh[i - 1], smesh[i], smap);

                for (j = 0; j < smesh[i - 1].Nt; j++)
                {
                    if (smap[j][0] > tempsize2 - 1)
                    {
                        Console.WriteLine("WARNING: tempsize2 for smap is too small!!\n");
                        goto stop;
                    }
                }

                smesh[i].Smap = new int[smesh[i - 1].Nt][];
                for (j = 0; j < smesh[i - 1].Nt; j++)
                {
                    smesh[i].Smap[j] = new int[smap[j][0] + 1];
                    for (k = 0; k <= smap[j][0]; k++)
                    {
                        smesh[i].Smap[j][k] = smap[j][k];
                    }
                }


                smesh[i].Cf = new double[smesh[i - 1].Nt][][][];
                for (j = 0; j < smesh[i - 1].Nt; j++)
                {
                    smesh[i].Cf[j] = new double[3][][];
                    for (k = 0; k < 3; k++)
                    {
                        smesh[i].Cf[j][k] = new double[smesh[i].Smap[j][0]][];
                        for (m = 0; m < smesh[i].Smap[j][0]; m++)
                        {
                            smesh[i].Cf[j][k][m] = new double[3];;
                        }
                    }
                }
                smesh[i].Fc = new double[smesh[i - 1].Nt][][][];
                for (j = 0; j < smesh[i - 1].Nt; j++)
                {
                    smesh[i].Fc[j] = new double[3][][];
                    for (k = 0; k < 3; k++)
                    {
                        smesh[i].Fc[j][k] = new double[smesh[i].Smap[j][0]][];
                        for (m = 0; m < smesh[i].Smap[j][0]; m++)
                        {
                            smesh[i].Fc[j][k][m] = new double[3];;
                        }
                    }
                }
                Mgrid.SpatialMapping2(smesh[i - 1], smesh[i], smesh[i].Smap, smesh[i].Cf, smesh[i].Fc, tempsize2);
            }

            // 2.3. compute "e", "e2", "so2", "n" and "ori"
            //      For the data structure of "eo", "e2","so2", "n" and "ori", see "boundary".
            for (i = 0; i <= sMeshLevel; i++)
            {
                smesh[i].E2 = new int[smesh[i].Ne][];
                for (j = 0; j < smesh[i].Ne; j++)
                {
                    smesh[i].E2[j] = new int[2];
                }
                smesh[i].So2 = new int[smesh[i].Nt][];
                for (j = 0; j < smesh[i].Nt; j++)
                {
                    smesh[i].So2[j] = new int[3];
                }
                smesh[i].N = new double[smesh[i].Ne][];
                for (j = 0; j < smesh[i].Ne; j++)
                {
                    smesh[i].N[j] = new double[2];
                }
                smesh[i].Ori = new int[smesh[i].Ne];

                Mgrid.Boundary(smesh[i].Ne, smesh[i].Nt, smesh[i].T, smesh[i].P2, smesh[i].P, smesh[i].E, smesh[i].E2, smesh[i].So2, smesh[i].N, smesh[i].Ori);
            }

            // 2.4. compute "bd" and "bd2"
            //      For the data structure of "bd" and "bd2", see "edgeterm".
            for (i = 0; i <= sMeshLevel; i++)
            {
                smesh[i].Bd = new int[amesh[aMeshLevel].Ns][][];
                for (j = 0; j < amesh[aMeshLevel].Ns; j++)
                {
                    smesh[i].Bd[j] = new int[smesh[i].Nt][];;
                    for (k = 0; k < smesh[i].Nt; k++)
                    {
                        smesh[i].Bd[j][k] = new int[9];
                        for (m = 0; m < 9; m++)
                        {
                            smesh[i].Bd[j][k][m] = -1;
                        }
                    }
                }
            }
            for (i = 0; i <= sMeshLevel; i++)
            {
                smesh[i].Bd2 = new double[amesh[aMeshLevel].Ns][][];
                for (j = 0; j < amesh[aMeshLevel].Ns; j++)
                {
                    smesh[i].Bd2[j] = new double[smesh[i].Nt][];
                    for (k = 0; k < smesh[i].Nt; k++)
                    {
                        smesh[i].Bd2[j][k] = new double[3];
                    }
                }
            }
            for (i = 0; i <= sMeshLevel; i++)
            {
                for (j = 0; j < amesh[aMeshLevel].Ns; j++)
                {
                    Mgrid.EdgeTri(smesh[i].Nt, amesh[aMeshLevel].Ang[j], smesh[i].P, smesh[i].P2, smesh[i].T, smesh[i].Bd[j], smesh[i].Bd2[j], smesh[i].So2);
                }
            }

            // 3.1. compute "noflevel"
            //      level: the mesh layers for multgrid; the bigger value represents finer mesh.
            //      noflevel[level][2]: the corresponding angular mesh level and spatial mesh level for each multigrid mesh level
            //      Example:    assume noflevel[i][0]=3 and noflevel[i][1]=2, then
            //                  the spatial mesh level is "3" and the angular mesh level is "2" on the multgrid mesh level "i".
            switch (mgMethod)
            {
            case 1:     //AMG
                for (i = 0; i <= level; i++)
                {
                    noflevel[i] = new int[2];
                }
                for (i = 0; i <= da; i++)
                {
                    noflevel[i][0] = sMeshLevel;
                    noflevel[i][1] = i + aMeshLevel0;
                }
                break;

            case 2:     //SMG
                for (i = 0; i <= level; i++)
                {
                    noflevel[i] = new int[2];
                }
                for (i = 0; i <= ds; i++)
                {
                    noflevel[i][0] = i + sMeshLevel0;
                    noflevel[i][1] = aMeshLevel;
                }
                break;

            case 3:     //MG1
                for (i = 0; i <= level; i++)
                {
                    noflevel[i] = new int[2];
                }
                if (ds > da)
                {
                    for (i = 0; i < ds - da; i++)
                    {
                        noflevel[i][0] = i + sMeshLevel0;
                        noflevel[i][1] = aMeshLevel0;
                    }
                    for (i = 0; i <= da; i++)
                    {
                        noflevel[i + ds - da][0] = i + ds - da + sMeshLevel0;
                        noflevel[i + ds - da][1] = i + aMeshLevel0;
                    }
                }
                else
                {
                    for (i = 0; i < da - ds; i++)
                    {
                        noflevel[i][0] = sMeshLevel0;
                        noflevel[i][1] = i + aMeshLevel0;
                    }
                    for (i = 0; i <= ds; i++)
                    {
                        noflevel[i + da - ds][0] = i + sMeshLevel0;
                        noflevel[i + da - ds][1] = i + da - ds + aMeshLevel0;
                    }
                }
                break;

            case 4:     //MG2
                for (i = 0; i <= level; i++)
                {
                    noflevel[i] = new int[2];
                }
                for (i = sMeshLevel0; i <= sMeshLevel; i++)
                {
                    noflevel[i - sMeshLevel0][0] = i;
                    noflevel[i - sMeshLevel0][1] = aMeshLevel0;
                }
                for (i = aMeshLevel0 + 1; i <= aMeshLevel; i++)
                {
                    noflevel[i - aMeshLevel0 + sMeshLevel - sMeshLevel0][0] = sMeshLevel;
                    noflevel[i - aMeshLevel0 + sMeshLevel - sMeshLevel0][1] = i;
                }
                break;

            case 5:     //MG3
                for (i = 0; i <= level; i++)
                {
                    noflevel[i] = new int[2];
                }
                for (i = aMeshLevel0; i <= aMeshLevel; i++)
                {
                    noflevel[i - aMeshLevel0][0] = sMeshLevel0;
                    noflevel[i - aMeshLevel0][1] = i;
                }
                for (i = sMeshLevel0 + 1; i <= sMeshLevel; i++)
                {
                    noflevel[i - sMeshLevel0 + aMeshLevel - aMeshLevel0][0] = i;
                    noflevel[i - sMeshLevel0 + aMeshLevel - aMeshLevel0][1] = aMeshLevel;
                }
                break;

            case 6:     //MG4_a
                for (i = 0; i <= level; i++)
                {
                    noflevel[i] = new int[2];
                }
                if (ds >= da)
                {
                    for (i = 0; i <= ds - da; i++)
                    {
                        noflevel[i][0] = i + sMeshLevel0;
                        noflevel[i][1] = aMeshLevel0;
                    }
                    for (i = 1; i <= da; i++)
                    {
                        noflevel[ds - da + 2 * i - 1][0] = sMeshLevel0 + ds - da + i;
                        noflevel[ds - da + 2 * i - 1][1] = aMeshLevel0 + i - 1;
                        noflevel[ds - da + 2 * i][0]     = sMeshLevel0 + ds - da + i;
                        noflevel[ds - da + 2 * i][1]     = aMeshLevel0 + i;
                    }
                }
                else
                {
                    for (i = 0; i <= da - ds; i++)
                    {
                        noflevel[i][0] = sMeshLevel0;
                        noflevel[i][1] = i + aMeshLevel0;
                    }
                    for (i = 1; i <= ds; i++)
                    {
                        noflevel[da - ds + 2 * i - 1][0] = sMeshLevel0 + i;
                        noflevel[da - ds + 2 * i - 1][1] = aMeshLevel0 + da - ds + i - 1;
                        noflevel[da - ds + 2 * i][0]     = sMeshLevel0 + i;
                        noflevel[da - ds + 2 * i][1]     = aMeshLevel0 + da - ds + i;
                    }
                }
                break;

            case 7:      //MG4_s
                for (i = 0; i <= level; i++)
                {
                    noflevel[i] = new int[2];
                }
                if (ds >= da)
                {
                    for (i = 0; i <= ds - da; i++)
                    {
                        noflevel[i][0] = i + sMeshLevel0;
                        noflevel[i][1] = aMeshLevel0;
                    }
                    for (i = 1; i <= da; i++)
                    {
                        noflevel[ds - da + 2 * i - 1][0] = sMeshLevel0 + ds - da + i - 1;
                        noflevel[ds - da + 2 * i - 1][1] = aMeshLevel0 + i;
                        noflevel[ds - da + 2 * i][0]     = sMeshLevel0 + ds - da + i;
                        noflevel[ds - da + 2 * i][1]     = aMeshLevel0 + i;
                    }
                }
                else
                {
                    for (i = 0; i <= da - ds; i++)
                    {
                        noflevel[i][0] = sMeshLevel0;
                        noflevel[i][1] = i + aMeshLevel0;
                    }
                    for (i = 1; i <= ds; i++)
                    {
                        noflevel[da - ds + 2 * i - 1][0] = sMeshLevel0 + i - 1;
                        noflevel[da - ds + 2 * i - 1][1] = aMeshLevel0 + da - ds + i;
                        noflevel[da - ds + 2 * i][0]     = sMeshLevel0 + i;
                        noflevel[da - ds + 2 * i][1]     = aMeshLevel0 + da - ds + i;
                    }
                }
                break;
            }

            // 3.2. malloc "ua", "us", "flux", "RHS", "d" and "q"
            //      ua[level][nt][2]:absorption coefficient
            //      us[level][nt][2]:scattering coefficient
            //      flux[level][ns][nt][2]: photon flux
            //      RHS[level][ns][nt][2]: source term
            //      d[level][ns][nt][2]: residual
            //      q[level][2][ns]: boundary source
            {
                for (i = sMeshLevel - 1; i >= 0; i--)
                {
                    ua[i] = new double[smesh[i].Nt][];
                    us[i] = new double[smesh[i].Nt][];
                    for (j = 0; j < smesh[i].Nt; j++)
                    {
                        ua[i][j] = new double[3];
                        us[i][j] = new double[3];
                    }
                    Mgrid.FtoC_s2(smesh[i].Nt, ua[i + 1], ua[i], smesh[i + 1].Smap, smesh[i + 1].Fc);
                    Mgrid.FtoC_s2(smesh[i].Nt, us[i + 1], us[i], smesh[i + 1].Smap, smesh[i + 1].Fc);
                }


                for (n = 0; n <= level; n++)
                {
                    nt     = smesh[noflevel[n][0]].Nt;
                    ns     = amesh[noflevel[n][1]].Ns;
                    RHS[n] = new double[ns][][];
                    for (i = 0; i < ns; i++)
                    {
                        RHS[n][i] = new double[nt][];
                        for (j = 0; j < nt; j++)
                        {
                            RHS[n][i][j] = new double[3];
                            for (k = 0; k < 3; k++)
                            {
                                RHS[n][i][j][k] = 0;
                            }
                        }
                    }
                }

                for (n = 0; n <= level; n++)
                {
                    nt   = smesh[noflevel[n][0]].Nt;
                    ns   = amesh[noflevel[n][1]].Ns;
                    d[n] = new double[ns][][];
                    for (i = 0; i < ns; i++)
                    {
                        d[n][i] = new double[nt][];
                        for (j = 0; j < nt; j++)
                        {
                            d[n][i][j] = new double[3];
                            for (k = 0; k < 3; k++)
                            {
                                d[n][i][j][k] = 0;
                            }
                        }
                    }
                }
                for (n = 0; n <= level; n++)
                {
                    nt      = smesh[noflevel[n][0]].Nt;
                    ns      = amesh[noflevel[n][1]].Ns;
                    flux[n] = new double[ns][][];
                    for (i = 0; i < ns; i++)
                    {
                        flux[n][i] = new double[nt][];
                        for (j = 0; j < nt; j++)
                        {
                            flux[n][i][j] = new double[3];
                            for (k = 0; k < 3; k++)
                            {
                                flux[n][i][j][k] = 0;
                            }
                        }
                    }
                }

                for (n = 0; n <= level; n++)
                {
                    ne   = smesh[noflevel[n][0]].Ne;
                    ns   = amesh[noflevel[n][1]].Ns;
                    q[n] = new double[ns][][];
                    for (i = 0; i < ns; i++)
                    {
                        q[n][i] = new double[ne][];
                        for (j = 0; j < ne; j++)
                        {
                            q[n][i][j] = new double[2];
                            for (k = 0; k < 2; k++)
                            {
                                q[n][i][j][k] = 0;
                            }
                        }
                    }
                }
            }


            // 3.3. compute "b"
            //      For the data structure of "b", see "boundarycoupling".
            if (vacuum == 0)// we need "b" only in the presence of refraction index mismatch at the domain boundary.
            {
                for (i = 0; i <= level; i++)
                {
                    ne = smesh[noflevel[i][0]].Ne;
                    ns = amesh[noflevel[i][1]].Ns;

                    b[i].Ri = new int[ne][][];
                    for (j = 0; j < ne; j++)
                    {
                        b[i].Ri[j] = new int[ns][];
                        for (k = 0; k < ns; k++)
                        {
                            b[i].Ri[j][k] = new int[2];
                        }
                    }

                    b[i].Si = new int[ne][][];
                    for (j = 0; j < ne; j++)
                    {
                        b[i].Si[j] = new int[ns][];
                        for (k = 0; k < ns; k++)
                        {
                            b[i].Si[j][k] = new int[2];
                        }
                    }

                    b[i].Ro = new int[ne][][];
                    for (j = 0; j < ne; j++)
                    {
                        b[i].Ro[j] = new int[ns][];
                        for (k = 0; k < ns; k++)
                        {
                            b[i].Ro[j][k] = new int[2];
                        }
                    }


                    b[i].So = new int[ne][][];
                    for (j = 0; j < ne; j++)
                    {
                        b[i].So[j] = new int[ns][];
                        for (k = 0; k < ns; k++)
                        {
                            b[i].So[j][k] = new int[2];
                        }
                    }

                    b[i].Ri2 = new double[ne][][];
                    for (j = 0; j < ne; j++)
                    {
                        b[i].Ri2[j] = new double[ns][];
                        for (k = 0; k < ns; k++)
                        {
                            b[i].Ri2[j][k] = new double[2];
                        }
                    }

                    b[i].Ro2 = new double[ne][][];
                    for (j = 0; j < ne; j++)
                    {
                        b[i].Ro2[j] = new double[ns][];
                        for (k = 0; k < ns; k++)
                        {
                            b[i].Ro2[j][k] = new double[2];
                        }
                    }

                    b[i].Si2 = new double[ne][][];
                    for (j = 0; j < ne; j++)
                    {
                        b[i].Si2[j] = new double[ns][];
                        for (k = 0; k < ns; k++)
                        {
                            b[i].Si2[j][k] = new double[2];
                        }
                    }

                    b[i].So2 = new double[ne][][];
                    for (j = 0; j < ne; j++)
                    {
                        b[i].So2[j] = new double[ns][];
                        for (k = 0; k < ns; k++)
                        {
                            b[i].So2[j][k] = new double[2];
                        }
                    }

                    Mgrid.BoundReflection(ns, amesh[noflevel[i][1]].Ang, smesh[noflevel[i][0]], nTissue, nExt, b[i]);
                }
            }
            stop :;
        }
示例#2
0
        /// <summary>
        /// Execute MG RTE solver
        /// </summary>
        /// <param name="input">Simulation inputs</param>
        /// <returns>measurements</returns>
        public static Measurement ExecuteMGRTE(SimulationInput input)
        {
            int    nMismatch;
            int    i, j, k, m, n;
            int    level;
            double res = 0, res0 = 1, rho = 1.0;
            int    ds = input.MeshDataInput.SMeshLevel - input.SimulationOptionsInput.StartingSmeshLevel;
            int    da = input.MeshDataInput.AMeshLevel - input.SimulationOptionsInput.StartingAmeshLevel;


            /* Read the initial time. */
            DateTime startTime1 = DateTime.Now;
            ILogger  logger     = LoggerFactoryLocator.GetDefaultNLogFactory().Create(typeof(SolverMGRTE));

            //  step 1: compute "level"
            //  level: the indicator of mesh levels in multigrid
            switch (input.SimulationOptionsInput.MethodMg)
            {
            case 1:
                level = da;
                break;

            case 2:     //SMG:
                level = ds;
                break;

            case 3:     //MG1:
                level = Math.Max(da, ds);
                break;

            case 4:     //MG2:
                level = ds + da;
                break;

            case 5:     //MG3:
                level = ds + da;
                break;

            case 6:     //MG4_a:
                level = ds + da;
                break;

            case 7:     //MG4_s:
                level = ds + da;
                break;

            default:
                level = -1;
                break;
            }


            //Create Dynamic arrays based on above values
            var amesh = new AngularMesh[input.MeshDataInput.AMeshLevel + 1];
            var smesh = new SpatialMesh[input.MeshDataInput.SMeshLevel + 1];
            var b     = new BoundaryCoupling[level + 1];

            var noflevel = new int[level + 1][];
            var ua       = new double[input.MeshDataInput.SMeshLevel + 1][][];
            var us       = new double[input.MeshDataInput.SMeshLevel + 1][][];
            var rhs      = new double[level + 1][][][];
            var d        = new double[level + 1][][][];
            var flux     = new double[level + 1][][][];
            var q        = new double[level + 1][][][];

            var mgrid  = new MultiGridCycle();
            var rteout = new OutputCalculation();

            var tissueInput = (MultiEllipsoidTissueInput)input.TissueInput;
            int incRegions  = tissueInput.EllipsoidRegions.Length;
            int tisRegions  = tissueInput.LayerRegions.Length;

            double depth = 0.0;

            for (i = 1; i < tissueInput.LayerRegions.Length - 1; i++)
            {
                depth += ((LayerTissueRegion)(tissueInput.LayerRegions[i])).ZRange.Stop - ((LayerTissueRegion)(tissueInput.LayerRegions[i])).ZRange.Start;
            }

            input.MeshDataInput.SideLength = depth;
            int totRegions = incRegions + tisRegions;

            //   MG-RTE does not converge when g = 1.0;
            for (i = 0; i < totRegions; i++)
            {
                if (input.TissueInput.Regions[i].RegionOP.G >= 1.0)
                {
                    input.TissueInput.Regions[i].RegionOP.G = 1.0 - 1e-5;
                }
            }

            // Check refractive index mismatch
            if (Math.Abs(input.TissueInput.Regions[0].RegionOP.N - input.TissueInput.Regions[1].RegionOP.N)
                / input.TissueInput.Regions[0].RegionOP.N < 0.01) // refraction index mismatch at the boundary
            {
                nMismatch = 1;
            }
            else
            {
                nMismatch = 0;
            }


            //Create spatial and angular mesh
            MathFunctions.CreateSquareMesh(ref smesh, input.MeshDataInput.SMeshLevel, depth);
            MathFunctions.AssignRegions(ref smesh, input.MeshDataInput.SMeshLevel, tissueInput);
            MathFunctions.CreateAnglularMesh(ref amesh, input.MeshDataInput.AMeshLevel, tissueInput);


            MathFunctions.SweepOrdering(ref smesh, amesh, input.MeshDataInput.SMeshLevel, input.MeshDataInput.AMeshLevel);
            MathFunctions.SetMus(ref us, smesh, input);
            MathFunctions.SetMua(ref ua, smesh, input);

            // load optical property, angular mesh, and spatial mesh files
            Initialization.Initial(
                ref amesh, ref smesh, ref flux, ref d,
                ref rhs, ref q, ref noflevel, ref b,
                level, input.SimulationOptionsInput.MethodMg, nMismatch, input.SimulationOptionsInput.NExternal,
                input.SimulationOptionsInput.NExternal, input.MeshDataInput.AMeshLevel, input.SimulationOptionsInput.StartingAmeshLevel,
                input.MeshDataInput.SMeshLevel, input.SimulationOptionsInput.StartingSmeshLevel, ua, us, mgrid);

            //Assign external source if available
            if (input.ExtSourceInput != null)
            {
                IExtSource extsource = FemSourceFactory.GetExtSource(input.ExtSourceInput);
                extsource.AssignMeshForExtSource(amesh, input.MeshDataInput.AMeshLevel, smesh, input.MeshDataInput.SMeshLevel, level, q);
            }

            //Assign internal source if available
            if (input.IntSourceInput != null)
            {
                //Assign an internal source
                IIntSource intsource = FemSourceFactory.GetIntSource(input.IntSourceInput);
                intsource.AssignMeshForIntSource(amesh, input.MeshDataInput.AMeshLevel, smesh, input.MeshDataInput.SMeshLevel, level, rhs);
            }

            /* Read the end time. */
            DateTime stopTime1 = DateTime.Now;
            /* Compute and print the duration of this first task. */
            TimeSpan duration1 = stopTime1 - startTime1;

            logger.Info(() => "Initlalization for RTE_2D takes " + duration1.TotalSeconds + " seconds\n");

            //step 2: RTE solver
            DateTime startTime2 = DateTime.Now;

            int ns = amesh[input.MeshDataInput.AMeshLevel].Ns;


            if (input.SimulationOptionsInput.FullMg == 1)
            {
                int nt1, ns1;
                int nt2 = smesh[noflevel[level][0]].Nt;
                int ns2 = amesh[noflevel[level][1]].Ns;

                for (n = level - 1; n >= 0; n--)
                {
                    nt1 = smesh[noflevel[n][0]].Nt;
                    ns1 = amesh[noflevel[n][1]].Ns;
                    if (nt1 == nt2)
                    {
                        mgrid.FtoC_a(nt1, ns1, rhs[n + 1], rhs[n]);
                    }
                    else
                    {
                        if (ns1 == ns2)
                        {
                            mgrid.FtoC_s(nt1, ns1, rhs[n + 1], rhs[n], smesh[noflevel[n][0] + 1].Smap, smesh[noflevel[n][0] + 1].Fc);
                        }
                        else
                        {
                            mgrid.FtoC(nt1, ns1, rhs[n + 1], rhs[n], smesh[noflevel[n][0] + 1].Smap, smesh[noflevel[n][0] + 1].Fc);
                        }
                    }
                    nt2 = nt1; ns2 = ns1;
                }

                nt1 = smesh[noflevel[0][0]].Nt;
                ns1 = amesh[noflevel[0][1]].Ns;

                for (n = 0; n < level; n++)
                {
                    if (input.SimulationOptionsInput.MethodMg == 6)
                    {
                        if (((level - n) % 2) == 0)
                        {
                            for (i = 0; i < input.SimulationOptionsInput.NCycle; i++)
                            {
                                res = mgrid.MgCycle(amesh, smesh, b, q, rhs, ua, us, flux, d, input.SimulationOptionsInput.NPreIterations, input.SimulationOptionsInput.NPostIterations,
                                                    noflevel[n][1], input.SimulationOptionsInput.StartingAmeshLevel, noflevel[n][0], input.SimulationOptionsInput.StartingSmeshLevel, ns, nMismatch, 6);
                            }
                        }
                        else
                        {
                            for (i = 0; i < input.SimulationOptionsInput.NCycle; i++)
                            {
                                mgrid.MgCycle(amesh, smesh, b, q, rhs, ua, us, flux, d, input.SimulationOptionsInput.NPreIterations, input.SimulationOptionsInput.NPostIterations,
                                              noflevel[n][1], input.SimulationOptionsInput.StartingAmeshLevel, noflevel[n][0], input.SimulationOptionsInput.StartingSmeshLevel, ns, nMismatch, 7);
                            }
                        }
                    }
                    else
                    {
                        if (input.SimulationOptionsInput.MethodMg == 7)
                        {
                            if (((level - n) % 2) == 0)
                            {
                                for (i = 0; i < input.SimulationOptionsInput.NCycle; i++)
                                {
                                    mgrid.MgCycle(amesh, smesh, b, q, rhs, ua, us, flux, d, input.SimulationOptionsInput.NPreIterations, input.SimulationOptionsInput.NPostIterations,
                                                  noflevel[n][1], input.SimulationOptionsInput.StartingAmeshLevel, noflevel[n][0], input.SimulationOptionsInput.StartingSmeshLevel, ns, nMismatch, 7);
                                }
                            }
                            else
                            {
                                for (i = 0; i < input.SimulationOptionsInput.NCycle; i++)
                                {
                                    mgrid.MgCycle(amesh, smesh, b, q, rhs, ua, us, flux, d, input.SimulationOptionsInput.NPreIterations, input.SimulationOptionsInput.NPostIterations,
                                                  noflevel[n][1], input.SimulationOptionsInput.StartingAmeshLevel, noflevel[n][0], input.SimulationOptionsInput.StartingSmeshLevel, ns, nMismatch, 6);
                                }
                            }
                        }
                        else
                        {
                            for (i = 0; i < input.SimulationOptionsInput.NCycle; i++)
                            {
                                mgrid.MgCycle(amesh, smesh, b, q, rhs, ua, us, flux, d, input.SimulationOptionsInput.NPreIterations, input.SimulationOptionsInput.NPostIterations,
                                              noflevel[n][1], input.SimulationOptionsInput.StartingAmeshLevel, noflevel[n][0], input.SimulationOptionsInput.StartingSmeshLevel, ns, nMismatch,
                                              input.SimulationOptionsInput.MethodMg);
                            }
                        }
                    }

                    nt2 = smesh[noflevel[n + 1][0]].Nt;
                    ns2 = amesh[noflevel[n + 1][1]].Ns;
                    if (nt1 == nt2)
                    {
                        mgrid.CtoF_a(nt1, ns1, flux[n + 1], flux[n]);
                    }
                    else
                    {
                        if (ns1 == ns2)
                        {
                            mgrid.CtoF_s(nt1, ns1, flux[n + 1], flux[n], smesh[noflevel[n][0] + 1].Smap, smesh[noflevel[n][0] + 1].Cf);
                        }
                        else
                        {
                            mgrid.CtoF(nt1, ns1, flux[n + 1], flux[n], smesh[noflevel[n][0] + 1].Smap, smesh[noflevel[n][0] + 1].Cf);
                        }
                    }
                    nt1 = nt2; ns1 = ns2;
                    for (m = 0; m <= n; m++)
                    {
                        for (i = 0; i < amesh[noflevel[m][1]].Ns; i++)
                        {
                            for (j = 0; j < smesh[noflevel[m][0]].Nt; j++)
                            {
                                for (k = 0; k < 3; k++)
                                {
                                    flux[m][i][j][k] = 0;
                                }
                            }
                        }
                    }
                }
            }

            // 2.2. multigrid solver on the finest mesh
            n = 0;

            while (n < input.SimulationOptionsInput.NIterations)
            {
                n++;
                res = mgrid.MgCycle(amesh, smesh, b, q, rhs, ua, us, flux, d, input.SimulationOptionsInput.NPreIterations, input.SimulationOptionsInput.NPostIterations, input.MeshDataInput.AMeshLevel,
                                    input.SimulationOptionsInput.StartingAmeshLevel, input.MeshDataInput.SMeshLevel, input.SimulationOptionsInput.StartingSmeshLevel, ns, nMismatch, input.SimulationOptionsInput.MethodMg);
                for (m = 0; m < level; m++)
                {
                    for (i = 0; i < amesh[noflevel[m][1]].Ns; i++)
                    {
                        for (j = 0; j < smesh[noflevel[m][0]].Nt; j++)
                        {
                            for (k = 0; k < 3; k++)
                            {
                                flux[m][i][j][k] = 0;
                            }
                        }
                    }
                }


                if (n > 1)
                {
                    rho *= res / res0;
                    logger.Info(() => "Iteration: " + n + ", Current tolerance: " + res + "\n");

                    if (res < input.SimulationOptionsInput.ConvTolerance)
                    {
                        rho = Math.Pow(rho, 1.0 / (n - 1));
                        n   = input.SimulationOptionsInput.NIterations;
                    }
                }
                else
                {
                    logger.Info(() => "Iteration: " + n + ", Current tolerance: " + res + "\n");
                    res0 = res;
                    if (res < input.SimulationOptionsInput.ConvTolerance)
                    {
                        n = input.SimulationOptionsInput.NIterations;
                    }
                }
            }

            // 2.3. compute the residual
            //Mgrid.Defect(amesh[para.AMeshLevel], smesh[para.SMeshLevel], ns, RHS[level], ua[para.SMeshLevel], us[para.SMeshLevel],
            //    flux[level], b[level], q[level], d[level], vacuum);
            //res = Mgrid.Residual(smesh[para.SMeshLevel].nt, amesh[para.AMeshLevel].ns, d[level], smesh[para.SMeshLevel].a);

            /* Read the start time. */
            DateTime stopTime2 = DateTime.Now;
            TimeSpan duration2 = stopTime2 - startTime2;
            TimeSpan duration3 = stopTime2 - startTime1;

            logger.Info(() => "Iteration time: " + duration2.TotalSeconds + "seconds\n");
            logger.Info(() => "Total time: " + duration3.TotalSeconds + "seconds, Final residual: " + res + "\n");

            // step 3: postprocessing
            // 3.1. output
            Measurement measurement = rteout.RteOutput(flux[level], q[level], amesh[input.MeshDataInput.AMeshLevel], smesh[input.MeshDataInput.SMeshLevel], b[level], nMismatch);

            return(measurement);
        }