1 #define PETSCMAT_DLL 2 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. 7 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. 11 12 Used by the sparse factorization routines in 13 src/mat/impls/baij/seq 14 15 */ 16 17 #include "petsc.h" 18 19 #undef __FUNCT__ 20 #define __FUNCT__ "LINPACKdgedi" 21 PetscErrorCode LINPACKdgedi(MatScalar *a,PetscInt n,PetscInt *ipvt,MatScalar *work) 22 { 23 PetscInt i__2,kb,kp1,nm1,i,j,k,l,ll,kn,knp1,jn1; 24 MatScalar *aa,*ax,*ay,tmp; 25 MatScalar t; 26 27 PetscFunctionBegin; 28 --work; 29 --ipvt; 30 a -= n + 1; 31 32 /* compute inverse(u) */ 33 34 for (k = 1; k <= n; ++k) { 35 kn = k*n; 36 knp1 = kn + k; 37 a[knp1] = 1.0 / a[knp1]; 38 t = -a[knp1]; 39 i__2 = k - 1; 40 aa = &a[1 + kn]; 41 for (ll=0; ll<i__2; ll++) aa[ll] *= t; 42 kp1 = k + 1; 43 if (n < kp1) continue; 44 ax = aa; 45 for (j = kp1; j <= n; ++j) { 46 jn1 = j*n; 47 t = a[k + jn1]; 48 a[k + jn1] = 0.; 49 ay = &a[1 + jn1]; 50 for (ll=0; ll<k; ll++) { 51 ay[ll] += t*ax[ll]; 52 } 53 } 54 } 55 56 /* form inverse(u)*inverse(l) */ 57 58 nm1 = n - 1; 59 if (nm1 < 1) { 60 PetscFunctionReturn(0); 61 } 62 for (kb = 1; kb <= nm1; ++kb) { 63 k = n - kb; 64 kn = k*n; 65 kp1 = k + 1; 66 aa = a + kn; 67 for (i = kp1; i <= n; ++i) { 68 work[i] = aa[i]; 69 aa[i] = 0.; 70 } 71 for (j = kp1; j <= n; ++j) { 72 t = work[j]; 73 ax = &a[j * n + 1]; 74 ay = &a[kn + 1]; 75 for (ll=0; ll<n; ll++) { 76 ay[ll] += t*ax[ll]; 77 } 78 } 79 l = ipvt[k]; 80 if (l != k) { 81 ax = &a[kn + 1]; 82 ay = &a[l * n + 1]; 83 for (ll=0; ll<n; ll++) { 84 tmp = ax[ll]; 85 ax[ll] = ay[ll]; 86 ay[ll] = tmp; 87 } 88 } 89 } 90 PetscFunctionReturn(0); 91 } 92 93