1 2 /* 3 This file creating by running f2c 4 linpack. this version dated 08/14/78 5 cleve moler, university of new mexico, argonne national lab. 6 7 Computes the inverse of a matrix given its factors and pivots 8 calculated by PetscLINPACKgefa(). Performed in-place for an n by n 9 dense matrix. 10 11 Used by the sparse factorization routines in 12 src/mat/impls/baij/seq 13 14 */ 15 16 #include <petscsys.h> 17 #include <petsc/private/kernels/blockinvert.h> 18 19 PETSC_INTERN PetscErrorCode PetscLINPACKgedi(MatScalar *a, PetscInt n, PetscInt *ipvt, MatScalar *work) 20 { 21 PetscInt i__2, kb, kp1, nm1, i, j, k, l, ll, kn, knp1, jn1; 22 MatScalar *aa, *ax, *ay, tmp; 23 MatScalar t; 24 25 PetscFunctionBegin; 26 --work; 27 --ipvt; 28 a -= n + 1; 29 30 /* compute inverse(u) */ 31 32 for (k = 1; k <= n; ++k) { 33 kn = k * n; 34 knp1 = kn + k; 35 a[knp1] = 1.0 / a[knp1]; 36 t = -a[knp1]; 37 i__2 = k - 1; 38 aa = &a[1 + kn]; 39 for (ll = 0; ll < i__2; ll++) aa[ll] *= t; 40 kp1 = k + 1; 41 if (n < kp1) continue; 42 ax = aa; 43 for (j = kp1; j <= n; ++j) { 44 jn1 = j * n; 45 t = a[k + jn1]; 46 a[k + jn1] = 0.; 47 ay = &a[1 + jn1]; 48 for (ll = 0; ll < k; ll++) ay[ll] += t * ax[ll]; 49 } 50 } 51 52 /* form inverse(u)*inverse(l) */ 53 54 nm1 = n - 1; 55 if (nm1 < 1) PetscFunctionReturn(PETSC_SUCCESS); 56 for (kb = 1; kb <= nm1; ++kb) { 57 k = n - kb; 58 kn = k * n; 59 kp1 = k + 1; 60 aa = a + kn; 61 for (i = kp1; i <= n; ++i) { 62 work[i] = aa[i]; 63 aa[i] = 0.; 64 } 65 for (j = kp1; j <= n; ++j) { 66 t = work[j]; 67 ax = &a[j * n + 1]; 68 ay = &a[kn + 1]; 69 for (ll = 0; ll < n; ll++) ay[ll] += t * ax[ll]; 70 } 71 l = ipvt[k]; 72 if (l != k) { 73 ax = &a[kn + 1]; 74 ay = &a[l * n + 1]; 75 for (ll = 0; ll < n; ll++) { 76 tmp = ax[ll]; 77 ax[ll] = ay[ll]; 78 ay[ll] = tmp; 79 } 80 } 81 } 82 PetscFunctionReturn(PETSC_SUCCESS); 83 } 84