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 18 #undef __FUNCT__ 19 #define __FUNCT__ "PetscLINPACKgedi" 20 PetscErrorCode PetscLINPACKgedi(MatScalar *a,PetscInt n,PetscInt *ipvt,MatScalar *work) 21 { 22 PetscInt i__2,kb,kp1,nm1,i,j,k,l,ll,kn,knp1,jn1; 23 MatScalar *aa,*ax,*ay,tmp; 24 MatScalar t; 25 26 PetscFunctionBegin; 27 --work; 28 --ipvt; 29 a -= n + 1; 30 31 /* compute inverse(u) */ 32 33 for (k = 1; k <= n; ++k) { 34 kn = k*n; 35 knp1 = kn + k; 36 a[knp1] = 1.0 / a[knp1]; 37 t = -a[knp1]; 38 i__2 = k - 1; 39 aa = &a[1 + kn]; 40 for (ll=0; ll<i__2; ll++) aa[ll] *= t; 41 kp1 = k + 1; 42 if (n < kp1) continue; 43 ax = aa; 44 for (j = kp1; j <= n; ++j) { 45 jn1 = j*n; 46 t = a[k + jn1]; 47 a[k + jn1] = 0.; 48 ay = &a[1 + jn1]; 49 for (ll=0; ll<k; ll++) { 50 ay[ll] += t*ax[ll]; 51 } 52 } 53 } 54 55 /* form inverse(u)*inverse(l) */ 56 57 nm1 = n - 1; 58 if (nm1 < 1) { 59 PetscFunctionReturn(0); 60 } 61 for (kb = 1; kb <= nm1; ++kb) { 62 k = n - kb; 63 kn = k*n; 64 kp1 = k + 1; 65 aa = a + kn; 66 for (i = kp1; i <= n; ++i) { 67 work[i] = aa[i]; 68 aa[i] = 0.; 69 } 70 for (j = kp1; j <= n; ++j) { 71 t = work[j]; 72 ax = &a[j * n + 1]; 73 ay = &a[kn + 1]; 74 for (ll=0; ll<n; ll++) { 75 ay[ll] += t*ax[ll]; 76 } 77 } 78 l = ipvt[k]; 79 if (l != k) { 80 ax = &a[kn + 1]; 81 ay = &a[l * n + 1]; 82 for (ll=0; ll<n; ll++) { 83 tmp = ax[ll]; 84 ax[ll] = ay[ll]; 85 ay[ll] = tmp; 86 } 87 } 88 } 89 PetscFunctionReturn(0); 90 } 91 92