public static double spiro_iter(SpiroSegment[] s, BandMatrix[] m, int[] perm, double[] v, int n, int nmat)
{
bool cyclic;
int i, j, jthl, jthr, jk0l, jk0r, jk1l, jk1r, jk2l, jk2r, jinc, jj, k, n_invert;
SpiroPointType ty0, ty1;
double dk, norm, th;
double[][] ends = { new double[4], new double[4] };
double[][][] derivs =
{
new double[2][] { new double[4], new double[4] },
new double[2][] { new double[4], new double[4] },
new double[2][] { new double[4], new double[4] },
new double[2][] { new double[4], new double[4] },
};
cyclic = s[0].Type != SpiroPointType.OpenContour && s[0].Type != SpiroPointType.Corner;
for (i = 0; i < nmat; i++)
{
v[i] = 0.0;
for (j = 0; j < 11; j++)
{
m[i].a[j] = 0.0;
}
for (j = 0; j < 5; j++)
{
m[i].al[j] = 0.0;
}
}
j = 0;
if (s[0].Type == SpiroPointType.G4)
{
jj = nmat - 2;
}
else if (s[0].Type == SpiroPointType.G2)
{
jj = nmat - 1;
}
else
{
jj = 0;
}
for (i = 0; i < n; i++)
{
ty0 = s[i].Type;
ty1 = s[i + 1].Type;
jinc = compute_jinc(ty0, ty1);
th = s[i].bend_th;
jthl = jk0l = jk1l = jk2l = -1;
jthr = jk0r = jk1r = jk2r = -1;
compute_pderivs(ref s[i], ends, derivs, jinc);
// constraints crossing left
if (ty0 == SpiroPointType.G4 || ty0 == SpiroPointType.G2 || ty0 == SpiroPointType.Left || ty0 == SpiroPointType.Right)
{
jthl = jj++;
jj %= nmat;
jk0l = jj++;
if (ty0 == SpiroPointType.G4)
{
jj %= nmat;
jk1l = jj++;
jk2l = jj++;
}
}
// constraints on left
if ((ty0 == SpiroPointType.Left || ty0 == SpiroPointType.Corner || ty0 == SpiroPointType.OpenContour || ty0 == SpiroPointType.G2) && jinc == 4)
{
if (ty0 != SpiroPointType.G2)
{
jk1l = jj++;
}
jk2l = jj++;
}
// constraints on right
if ((ty1 == SpiroPointType.Right || ty1 == SpiroPointType.Corner || ty1 == SpiroPointType.EndOpenContour || ty1 == SpiroPointType.G2) && jinc == 4)
{
if (ty1 != SpiroPointType.G2)
{
jk1r = jj++;
}
jk2r = jj++;
}
// constraints crossing right
if (ty1 == SpiroPointType.G4 || ty1 == SpiroPointType.G2 || ty1 == SpiroPointType.Left || ty1 == SpiroPointType.Right)
{
jthr = jj;
jk0r = (jj + 1) % nmat;
if (ty1 == SpiroPointType.G4)
{
jk1r = (jj + 2) % nmat;
jk2r = (jj + 3) % nmat;
}
}
add_mat_line(m, v, derivs[0][0], th - ends[0][0], 1, j, jthl, jinc, nmat);
add_mat_line(m, v, derivs[1][0], ends[0][1], -1, j, jk0l, jinc, nmat);
add_mat_line(m, v, derivs[2][0], ends[0][2], -1, j, jk1l, jinc, nmat);
add_mat_line(m, v, derivs[3][0], ends[0][3], -1, j, jk2l, jinc, nmat);
add_mat_line(m, v, derivs[0][1], -ends[1][0], 1, j, jthr, jinc, nmat);
add_mat_line(m, v, derivs[1][1], -ends[1][1], 1, j, jk0r, jinc, nmat);
add_mat_line(m, v, derivs[2][1], -ends[1][2], 1, j, jk1r, jinc, nmat);
add_mat_line(m, v, derivs[3][1], -ends[1][3], 1, j, jk2r, jinc, nmat);
if (jthl >= 0)
{
v[jthl] = mod_2pi(v[jthl]);
}
if (jthr >= 0)
{
v[jthr] = mod_2pi(v[jthr]);
}
j += jinc;
}
if (cyclic)
{
BandMatrix.Copy(m, 0, m, nmat, nmat);
BandMatrix.Copy(m, 0, m, 2 * nmat, nmat);
Array.Copy(v, 0, v, nmat, nmat);
Array.Copy(v, 0, v, 2 * nmat, nmat);
n_invert = 3 * nmat;
j = nmat;
}
else
{
n_invert = nmat;
j = 0;
}
bandec11(m, perm, n_invert);
banbks11(m, perm, v, n_invert);
norm = 0.0;
for (i = 0; i < n; i++)
{
jinc = compute_jinc(s[i].Type, s[i + 1].Type);
for (k = 0; k < jinc; k++)
{
dk = v[j++];
s[i].ks[k] += dk;
norm += dk * dk;
}
s[i].ks[0] = 2.0 * mod_2pi(s[i].ks[0] / 2.0);
}
return(norm);
}
