1 /* 2 This file creating by running f2c 3 linpack. this version dated 08/14/78 4 cleve moler, university of new mexico, argonne national lab. 5 6 Computes the inverse of a matrix given its factors and pivots 7 calculated by PetscLINPACKgefa(). Performed in-place for an n by n 8 dense matrix. 9 10 Used by the sparse factorization routines in 11 src/mat/impls/baij/seq 12 13 */ 14 15 #include <petscsys.h> 16 #include <petsc/private/kernels/blockinvert.h> 17 18 PETSC_INTERN PetscErrorCode PetscLINPACKgedi(MatScalar *a, PetscInt n, PetscInt *ipvt, MatScalar *work) 19 { 20 PetscInt i__2, kb, kp1, nm1, i, j, k, l, ll, kn, knp1, jn1; 21 MatScalar *aa, *ax, *ay, tmp; 22 MatScalar t; 23 24 PetscFunctionBegin; 25 --work; 26 --ipvt; 27 a -= n + 1; 28 29 /* compute inverse(u) */ 30 31 for (k = 1; k <= n; ++k) { 32 kn = k * n; 33 knp1 = kn + k; 34 a[knp1] = 1.0 / a[knp1]; 35 t = -a[knp1]; 36 i__2 = k - 1; 37 aa = &a[1 + kn]; 38 for (ll = 0; ll < i__2; ll++) aa[ll] *= t; 39 kp1 = k + 1; 40 if (n < kp1) continue; 41 ax = aa; 42 for (j = kp1; j <= n; ++j) { 43 jn1 = j * n; 44 t = a[k + jn1]; 45 a[k + jn1] = 0.; 46 ay = &a[1 + jn1]; 47 for (ll = 0; ll < k; ll++) ay[ll] += t * ax[ll]; 48 } 49 } 50 51 /* form inverse(u)*inverse(l) */ 52 53 nm1 = n - 1; 54 if (nm1 < 1) PetscFunctionReturn(PETSC_SUCCESS); 55 for (kb = 1; kb <= nm1; ++kb) { 56 k = n - kb; 57 kn = k * n; 58 kp1 = k + 1; 59 aa = a + kn; 60 for (i = kp1; i <= n; ++i) { 61 work[i] = aa[i]; 62 aa[i] = 0.; 63 } 64 for (j = kp1; j <= n; ++j) { 65 t = work[j]; 66 ax = &a[j * n + 1]; 67 ay = &a[kn + 1]; 68 for (ll = 0; ll < n; ll++) ay[ll] += t * ax[ll]; 69 } 70 l = ipvt[k]; 71 if (l != k) { 72 ax = &a[kn + 1]; 73 ay = &a[l * n + 1]; 74 for (ll = 0; ll < n; ll++) { 75 tmp = ax[ll]; 76 ax[ll] = ay[ll]; 77 ay[ll] = tmp; 78 } 79 } 80 } 81 PetscFunctionReturn(PETSC_SUCCESS); 82 } 83