public static void gaussj(MatrixStruct a, int n, MatrixStruct b, int m)
{
int i, icol = 0, irow = 0, j, k, l, ll;
double big = 0.0, dum = 0.0, pivinv = 0.0;
int[] indxc = new int[3];
int[] indxr = new int[3];
int[] ipiv = new int[3];
for (j = 0; j < n; j++)
{
ipiv[j] = 0;
}
for (i = 0; i < n; i++)
{
big = 0.0;
for (j = 0; j < n; j++)
{
if (ipiv[j] != 1)
{
for (k = 0; k < n; k++)
{
if (ipiv[k] == 0)
{
if (Math.Abs(a.arr[j, k]) >= big)
{
big = Math.Abs(a.arr[j, k]);
irow = j;
icol = k;
}
}
else if (ipiv[k] > 1)
{
Console.WriteLine("GAUSSJ: Singular matrix-1\n");
}
}
}
}
++(ipiv[icol]);
if (irow != icol)
{
for (l = 0; l < n; l++)
{
swap(a.arr[irow, l], a.arr[icol, l]);
}
for (l = 0; l < m; l++)
{
swap(b.arr[irow, l], b.arr[icol, l]);
}
}
indxr[i] = irow;
indxc[i] = icol;
if (a.arr[icol, icol] == 0.0)
{
Console.WriteLine("GAUSSJ: Singular Matrix-2. icol is {0}\n", icol);
}
pivinv = 1.0 / a.arr[icol, icol];
a.arr[icol, icol] = 1.0;
for (l = 0; l < n; l++)
{
a.arr[icol, l] *= pivinv;
}
for (l = 0; l < m; l++)
{
b.arr[icol, l] *= pivinv;
}
for (ll = 0; ll < n; ll++)
{
if (ll != icol)
{
dum = a.arr[ll, icol];
a.arr[ll, icol] = 0.0;
for (l = 0; l < n; l++)
{
a.arr[ll, l] -= a.arr[icol, l] * dum;
}
for (l = 0; l < m; l++)
{
b.arr[ll, l] -= b.arr[icol, l] * dum;
}
}
}
}
for (l = n - 1; l >= 0; l--)
{
if (indxr[l] != indxc[l])
{
for (k = 0; k < n; k++)
{
swap(a.arr[k, indxr[l]], a.arr[k, indxc[l]]);
}
}
}
}
public static int Main()
{
bool pass = false;
Console.WriteLine("Solving AX=B and the inverse of A with Gauss-Jordan algorithm");
int n = 3;
int m = 1;
MatrixStruct a = new MatrixStruct(3, 3);
MatrixStruct b = new MatrixStruct(3, 1);
a.arr[0, 0] = 1;
a.arr[0, 1] = 1;
a.arr[0, 2] = 1;
a.arr[1, 0] = 1;
a.arr[1, 1] = 2;
a.arr[1, 2] = 4;
a.arr[2, 0] = 1;
a.arr[2, 1] = 3;
a.arr[2, 2] = 9;
b.arr[0, 0] = -1;
b.arr[1, 0] = 3;
b.arr[2, 0] = 3;
/*
int i, j;
Console.WriteLine("Matrix A is \n");
for (i=0; i<n; i++)
{
for (j=0; j<n; j++)
Console.Write("{0}\t", a.arr[i,j]);
Console.WriteLine();
}
Console.WriteLine();
Console.WriteLine("Matrix B is:\n");
for (i=0; i<n; i++)
{
for (j=0; j<m; j++)
Console.Write("{0}\t", b.arr[i,j]);
Console.WriteLine();
}
*/
gaussj(a, n, b, m);
/*
Console.WriteLine();
Console.WriteLine("The inverse of matrix A is:\n");
for (i=0; i<n; i++)
{
for (j=0; j<n; j++)
Console.Write("{0}\t", a.arr[i,j]);
Console.WriteLine();
}
Console.WriteLine();
Console.WriteLine("The solution X of AX=B is:\n");
for (i=0; i<n; i++)
{
for (j=0; j<m; j++)
Console.Write("{0}\t", b.arr[i,j]);
Console.WriteLine();
}
*/
if (
AreEqual(a.arr[0, 0], 3)
&& AreEqual(a.arr[1, 1], 4)
&& AreEqual(b.arr[0, 0], -9)
&& AreEqual(b.arr[1, 0], 10)
)
pass = true;
if (!pass)
{
Console.WriteLine("FAILED");
return 1;
}
else
{
Console.WriteLine("PASSED");
return 100;
}
}
public static int Main()
{
bool pass = false;
Console.WriteLine("Solving AX=B and the inverse of A with Gauss-Jordan algorithm");
int n = 3;
int m = 1;
MatrixStruct a = new MatrixStruct(3, 3);
MatrixStruct b = new MatrixStruct(3, 1);
a.arr[0, 0] = 1;
a.arr[0, 1] = 1;
a.arr[0, 2] = 1;
a.arr[1, 0] = 1;
a.arr[1, 1] = 2;
a.arr[1, 2] = 4;
a.arr[2, 0] = 1;
a.arr[2, 1] = 3;
a.arr[2, 2] = 9;
b.arr[0, 0] = -1;
b.arr[1, 0] = 3;
b.arr[2, 0] = 3;
/*
* int i, j;
*
* Console.WriteLine("Matrix A is \n");
* for (i=0; i<n; i++)
* {
* for (j=0; j<n; j++)
* Console.Write("{0}\t", a.arr[i,j]);
* Console.WriteLine();
* }
*
* Console.WriteLine();
* Console.WriteLine("Matrix B is:\n");
* for (i=0; i<n; i++)
* {
* for (j=0; j<m; j++)
* Console.Write("{0}\t", b.arr[i,j]);
* Console.WriteLine();
* }
*/
gaussj(a, n, b, m);
/*
* Console.WriteLine();
* Console.WriteLine("The inverse of matrix A is:\n");
* for (i=0; i<n; i++)
* {
* for (j=0; j<n; j++)
* Console.Write("{0}\t", a.arr[i,j]);
* Console.WriteLine();
* }
*
* Console.WriteLine();
* Console.WriteLine("The solution X of AX=B is:\n");
* for (i=0; i<n; i++)
* {
* for (j=0; j<m; j++)
* Console.Write("{0}\t", b.arr[i,j]);
* Console.WriteLine();
* }
*/
if (
AreEqual(a.arr[0, 0], 3) &&
AreEqual(a.arr[1, 1], 4) &&
AreEqual(b.arr[0, 0], -9) &&
AreEqual(b.arr[1, 0], 10)
)
{
pass = true;
}
if (!pass)
{
Console.WriteLine("FAILED");
return(1);
}
else
{
Console.WriteLine("PASSED");
return(100);
}
}
public static void gaussj(MatrixStruct a, int n, MatrixStruct b, int m)
{
int i, icol = 0, irow = 0, j, k, l, ll;
double big = 0.0, dum = 0.0, pivinv = 0.0;
int[] indxc = new int[3];
int[] indxr = new int[3];
int[] ipiv = new int[3];
for (j = 0; j < n; j++)
ipiv[j] = 0;
for (i = 0; i < n; i++)
{
big = 0.0;
for (j = 0; j < n; j++)
if (ipiv[j] != 1)
for (k = 0; k < n; k++)
{
if (ipiv[k] == 0)
{
if (Math.Abs(a.arr[j, k]) >= big)
{
big = Math.Abs(a.arr[j, k]);
irow = j;
icol = k;
}
}
else if (ipiv[k] > 1)
Console.WriteLine("GAUSSJ: Singular matrix-1\n");
}
++(ipiv[icol]);
if (irow != icol)
{
for (l = 0; l < n; l++) swap(a.arr[irow, l], a.arr[icol, l]);
for (l = 0; l < m; l++) swap(b.arr[irow, l], b.arr[icol, l]);
}
indxr[i] = irow;
indxc[i] = icol;
if (a.arr[icol, icol] == 0.0)
Console.WriteLine("GAUSSJ: Singular Matrix-2. icol is {0}\n", icol);
pivinv = 1.0 / a.arr[icol, icol];
a.arr[icol, icol] = 1.0;
for (l = 0; l < n; l++) a.arr[icol, l] *= pivinv;
for (l = 0; l < m; l++) b.arr[icol, l] *= pivinv;
for (ll = 0; ll < n; ll++)
if (ll != icol)
{
dum = a.arr[ll, icol];
a.arr[ll, icol] = 0.0;
for (l = 0; l < n; l++) a.arr[ll, l] -= a.arr[icol, l] * dum;
for (l = 0; l < m; l++) b.arr[ll, l] -= b.arr[icol, l] * dum;
}
}
for (l = n - 1; l >= 0; l--)
{
if (indxr[l] != indxc[l])
for (k = 0; k < n; k++)
swap(a.arr[k, indxr[l]], a.arr[k, indxc[l]]);
}
}
