1 #ifdef PETSC_RCS_HEADER 2 static char vcid[] = "$Id: dgedi.c,v 1.7 1997/10/19 03:26:08 bsmith Exp bsmith $"; 3 #endif 4 5 /* 6 This file creating by running f2c 7 linpack. this version dated 08/14/78 8 cleve moler, university of new mexico, argonne national lab. 9 10 Computes the inverse of a matrix given its factors and pivots 11 calculated by Linpack_DGEFA(). 12 */ 13 14 #include "petsc.h" 15 16 #undef __FUNC__ 17 #define __FUNC__ "Linpack_DGEDI" 18 int Linpack_DGEDI(Scalar *a,int n,int *ipvt,Scalar *work) 19 { 20 int i__2,kb, kp1, nm1,i, j, k, l, ll,kn,knp1,jn1; 21 Scalar t, *aa,*ax,*ay,tmp; 22 23 PetscFunctionBegin; 24 --work; 25 --ipvt; 26 a -= n + 1; 27 28 /* compute inverse(u) */ 29 30 for (k = 1; k <= n; ++k) { 31 kn = k*n; 32 knp1 = kn + k; 33 a[knp1] = 1.0 / a[knp1]; 34 t = -a[knp1]; 35 i__2 = k - 1; 36 aa = &a[1 + kn]; 37 for ( ll=0; ll<i__2; ll++ ) aa[ll] *= t; 38 kp1 = k + 1; 39 if (n < kp1) continue; 40 ax = aa; 41 for (j = kp1; j <= n; ++j) { 42 jn1 = j*n; 43 t = a[k + jn1]; 44 a[k + jn1] = 0.; 45 ay = &a[1 + jn1]; 46 for ( ll=0; ll<k; ll++ ) { 47 ay[ll] += t*ax[ll]; 48 } 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++ ) { 72 ay[ll] += t*ax[ll]; 73 } 74 } 75 l = ipvt[k]; 76 if (l != k) { 77 ax = &a[kn + 1]; 78 ay = &a[l * n + 1]; 79 for ( ll=0; ll<n; ll++ ) { 80 tmp = ax[ll]; 81 ax[ll] = ay[ll]; 82 ay[ll] = tmp; 83 } 84 } 85 } 86 PetscFunctionReturn(0); 87 } 88 89