//C = A * B
public static _Matrix multiply(_Matrix A, _Matrix B)
{
float temp = 0;
_Matrix C = new _Matrix(A.m, B.n);
if (A.n == B.m)
{
for (int i = 0; i < C.m; i++)
{
for (int j = 0; j < C.n; j++)
{
temp = 0;
for (int k = 0; k < A.n; k++)
{
temp += A.read(i, k) * B.read(k, j);
}
C.write(i, j, temp);
}
}
}
else
{
throw new System.Exception("Two martixs' row and column not equal");
}
return(C);
}
//calculate transposition Matrix,B = AT
public static _Matrix transpositionMatrix(_Matrix A)
{
_Matrix B = new _Matrix(A.n, A.m);
for (int i = 0; i < B.m; i++)
{
for (int j = 0; j < B.n; j++)
{
B.write(i, j, A.read(j, i));
}
}
return(B);
}
//calculate the det of a 2*2 matrix
public static float detTwoTwo(_Matrix A)
{
float value = 0;
//check if the matrix's def can be caculated
if (A.m != A.n || (A.m != 2))
{
throw new System.Exception("Can't calculate this matrix's def");
}
value = A.read(0, 0) * A.read(1, 1) - A.read(0, 1) * A.read(1, 0);
return(value);
}
//this get inverse matrix code is from https://www.cnblogs.com/renge-blogs/p/6308912.html
public static _Matrix Inverse(_Matrix matrix)
{
int m = matrix.m;
int n = matrix.n;
float[,] array = new float[2 * m + 1, 2 * n + 1];
for (int k = 0; k < 2 * m + 1; k++) //Initialize
{
for (int t = 0; t < 2 * n + 1; t++)
{
array[k, t] = 0f;
}
}
for (int i = 0; i < m; i++)
{
for (int j = 0; j < n; j++)
{
array[i, j] = matrix.read(i, j);
}
}
for (int k = 0; k < m; k++)
{
for (int t = n; t <= 2 * n; t++)
{
if ((t - k) == m)
{
array[k, t] = 1f;
}
else
{
array[k, t] = 0;
}
}
}
//get inverse matrix
for (int k = 0; k < m; k++)
{
if (array[k, k] != 1)
{
float bs = array[k, k];
array[k, k] = 1;
for (int p = k + 1; p < 2 * n; p++)
{
array[k, p] /= bs;
}
}
for (int q = 0; q < m; q++)
{
if (q != k)
{
float bs = array[q, k];
for (int p = 0; p < 2 * n; p++)
{
array[q, p] -= bs * array[k, p];
}
}
else
{
continue;
}
}
}
_Matrix inverse = new _Matrix(m, n);
for (int x = 0; x < m; x++)
{
for (int y = n; y < 2 * n; y++)
{
inverse.write(x, y - n, array[x, y]);
}
}
return(inverse);
}
