int RbfInvMatrix(RbfFloatMatrix *m)
{
register int i, j;
register int *indx;
register float *b;
register int tmp_err;
RbfFloatMatrix help;
#ifdef DEBUG_MODE
if (m -> rows != m -> columns)
ErrMess("RbfInvMatrix: matrix not of form N x N.\n");
#endif
if (!RbfAllocMatrix(m -> rows, m -> rows, &help) ||
(indx = (int *) malloc(m -> rows * sizeof(int))) == NULL ||
(b = (float *) malloc(m -> rows * sizeof(float))) == NULL)
{
ErrMess("RbfInvMatrix: impossible to allocate helpmatrix.\n");
return KRERR_INSUFFICIENT_MEM;
}
RbfSetMatrix(&help, m);
if ((tmp_err = RbfLUDcmp(&help, indx)) != 1)
{
free(b);
free(indx);
RbfFreeMatrix(&help);
return tmp_err;
}
for (j = 0; j < m -> rows; j++)
{
for (i = 0; i < m -> rows; i++)
b[i] = 0.0;
b[j] = 1.0;
RbfLUBksb(&help, indx, b);
for (i = 0; i < m -> rows; i++)
RbfMatrixSetValue(m, i, j, b[i]);
}
free(b);
free(indx);
RbfFreeMatrix(&help);
return 1;
}
int SnnsCLib::RbfInvMatrix(RbfFloatMatrix *m)
{
RbfFloatMatrix help;
int i, j, r, k, n;
float max, hr, hi;
#ifdef DEBUG_MODE
if (m -> rows != m -> columns)
ErrMess(const_cast<char*>("RbfInvMatrix: matrix not of form N x N.\n"));
#endif
n = m -> rows; /* n = dimension of matrix */
/* allocate helpmatrix: 0. row: field p[N] of algorithm */
/* 1. row: field hv[N] of algorithm */
if (!RbfAllocMatrix(2, n, &help))
{
ErrMess(const_cast<char*>("RbfInvMatrix: impossible to allocate helpmatrix.\n"));
return KRERR_INSUFFICIENT_MEM;
}
/* initialize permutation field: */
for (j = 0; j < n; j++)
RbfMatrixSetValue(&help, 0, j, (float) j);
/* invert matrix: */
/* notation in comments: m[r,c] means element at row r column c */
for (j = 0; j < n; j++)
{
/* looking for pivot: */
/* find row r, where r >= j and m[r,j] is maximal */
max = fabs(RbfMatrixGetValue(m, j, j));
r = j;
for (i = j+1; i < n; i++)
{
hi = fabs(RbfMatrixGetValue(m, j, i));
if (hi > max)
{
max = hi;
r = i;
}
}
/* test if matrix is singulary: */
/* if true, then return directly and report errorcode */
if (max == 0.0)
{
RbfFreeMatrix(&help);
return 0;
}
/* if r != j (r > j) then switch row r with row j and mark */
/* this in helpmatrix: */
if (r > j)
{
for (k = 0; k < n; k++)
{
hr = RbfMatrixGetValue(m, j, k);
RbfMatrixSetValue(m, j, k, RbfMatrixGetValue(m, r, k));
RbfMatrixSetValue(m, r, k, hr);
}
hi = RbfMatrixGetValue(&help, 0, j);
RbfMatrixSetValue(&help, 0, j, RbfMatrixGetValue(&help, 0, r));
RbfMatrixSetValue(&help, 0, r, hi);
}
/* do the transformation: */
hr = 1.0 / RbfMatrixGetValue(m, j, j);
for (i = 0; i < n; i++)
{
RbfMatrixSetValue(m, i, j, hr * RbfMatrixGetValue(m, i, j));
}
RbfMatrixSetValue(m, j, j, hr);
for (k = 0; k < n; k++)
if (k != j)
{
for (i = 0; i < n; i++)
if (i != j)
{
RbfMatrixSetValue(m, i, k,
RbfMatrixGetValue(m, i, k) -
RbfMatrixGetValue(m, i, j) *
RbfMatrixGetValue(m, j, k));
}
RbfMatrixSetValue(m, j, k,
-hr * RbfMatrixGetValue(m, j, k));
}
}
/* now switch back the columns: */
for (i = 0; i < n; i++)
{
for (k = 0; k < n; k++)
RbfMatrixSetValue(&help, 1,
(int) RbfMatrixGetValue(&help, 0, k),
RbfMatrixGetValue(m, i, k));
for (k = 0; k < n; k++)
RbfMatrixSetValue(m, i, k,
RbfMatrixGetValue(&help, 1, k));
}
/* report success: */
RbfFreeMatrix(&help);
return 1;
}
