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) { 56 PetscFunctionReturn(0); 57 } 58 for (kb = 1; kb <= nm1; ++kb) { 59 k = n - kb; 60 kn = k*n; 61 kp1 = k + 1; 62 aa = a + kn; 63 for (i = kp1; i <= n; ++i) { 64 work[i] = aa[i]; 65 aa[i] = 0.; 66 } 67 for (j = kp1; j <= n; ++j) { 68 t = work[j]; 69 ax = &a[j * n + 1]; 70 ay = &a[kn + 1]; 71 for (ll=0; ll<n; ll++) ay[ll] += t*ax[ll]; 72 } 73 l = ipvt[k]; 74 if (l != k) { 75 ax = &a[kn + 1]; 76 ay = &a[l * n + 1]; 77 for (ll=0; ll<n; ll++) { 78 tmp = ax[ll]; 79 ax[ll] = ay[ll]; 80 ay[ll] = tmp; 81 } 82 } 83 } 84 PetscFunctionReturn(0); 85 } 86 87