Actual source code: dgedi.c
1: #define PETSCMAT_DLL
3: /*
4: This file creating by running f2c
5: linpack. this version dated 08/14/78
6: cleve moler, university of new mexico, argonne national lab.
8: Computes the inverse of a matrix given its factors and pivots
9: calculated by LINPACKdgefa(). Performed in-place for an n by n
10: dense matrix.
12: Used by the sparse factorization routines in
13: src/mat/impls/baij/seq
15: See also src/inline/ilu.h
16: */
18: #include petsc.h
22: PetscErrorCode LINPACKdgedi(MatScalar *a,PetscInt n,PetscInt *ipvt,MatScalar *work)
23: {
24: PetscInt i__2,kb,kp1,nm1,i,j,k,l,ll,kn,knp1,jn1;
25: MatScalar *aa,*ax,*ay,tmp;
26: MatScalar t;
29: --work;
30: --ipvt;
31: a -= n + 1;
33: /* compute inverse(u) */
35: for (k = 1; k <= n; ++k) {
36: kn = k*n;
37: knp1 = kn + k;
38: a[knp1] = 1.0 / a[knp1];
39: t = -a[knp1];
40: i__2 = k - 1;
41: aa = &a[1 + kn];
42: for (ll=0; ll<i__2; ll++) aa[ll] *= t;
43: kp1 = k + 1;
44: if (n < kp1) continue;
45: ax = aa;
46: for (j = kp1; j <= n; ++j) {
47: jn1 = j*n;
48: t = a[k + jn1];
49: a[k + jn1] = 0.;
50: ay = &a[1 + jn1];
51: for (ll=0; ll<k; ll++) {
52: ay[ll] += t*ax[ll];
53: }
54: }
55: }
57: /* form inverse(u)*inverse(l) */
59: nm1 = n - 1;
60: if (nm1 < 1) {
61: return(0);
62: }
63: for (kb = 1; kb <= nm1; ++kb) {
64: k = n - kb;
65: kn = k*n;
66: kp1 = k + 1;
67: aa = a + kn;
68: for (i = kp1; i <= n; ++i) {
69: work[i] = aa[i];
70: aa[i] = 0.;
71: }
72: for (j = kp1; j <= n; ++j) {
73: t = work[j];
74: ax = &a[j * n + 1];
75: ay = &a[kn + 1];
76: for (ll=0; ll<n; ll++) {
77: ay[ll] += t*ax[ll];
78: }
79: }
80: l = ipvt[k];
81: if (l != k) {
82: ax = &a[kn + 1];
83: ay = &a[l * n + 1];
84: for (ll=0; ll<n; ll++) {
85: tmp = ax[ll];
86: ax[ll] = ay[ll];
87: ay[ll] = tmp;
88: }
89: }
90: }
91: return(0);
92: }