1 #ifdef PETSC_RCS_HEADER 2 static char vcid[] = "$Id: dgedi.c,v 1.8 1998/04/21 17:47:46 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(MatScalar *a,int n,int *ipvt,MatScalar *work) 19 { 20 int i__2,kb, kp1, nm1,i, j, k, l, ll,kn,knp1,jn1; 21 MatScalar *aa,*ax,*ay,tmp; 22 MatScalar t; 23 24 PetscFunctionBegin; 25 --work; 26 --ipvt; 27 a -= n + 1; 28 29 /* compute inverse(u) */ 30 31 for (k = 1; k <= n; ++k) { 32 kn = k*n; 33 knp1 = kn + k; 34 a[knp1] = 1.0 / a[knp1]; 35 t = -a[knp1]; 36 i__2 = k - 1; 37 aa = &a[1 + kn]; 38 for ( ll=0; ll<i__2; ll++ ) aa[ll] *= t; 39 kp1 = k + 1; 40 if (n < kp1) continue; 41 ax = aa; 42 for (j = kp1; j <= n; ++j) { 43 jn1 = j*n; 44 t = a[k + jn1]; 45 a[k + jn1] = 0.; 46 ay = &a[1 + jn1]; 47 for ( ll=0; ll<k; ll++ ) { 48 ay[ll] += t*ax[ll]; 49 } 50 } 51 } 52 53 /* form inverse(u)*inverse(l) */ 54 55 nm1 = n - 1; 56 if (nm1 < 1) { 57 PetscFunctionReturn(0); 58 } 59 for (kb = 1; kb <= nm1; ++kb) { 60 k = n - kb; 61 kn = k*n; 62 kp1 = k + 1; 63 aa = a + kn; 64 for (i = kp1; i <= n; ++i) { 65 work[i] = aa[i]; 66 aa[i] = 0.; 67 } 68 for (j = kp1; j <= n; ++j) { 69 t = work[j]; 70 ax = &a[j * n + 1]; 71 ay = &a[kn + 1]; 72 for ( ll=0; ll<n; ll++ ) { 73 ay[ll] += t*ax[ll]; 74 } 75 } 76 l = ipvt[k]; 77 if (l != k) { 78 ax = &a[kn + 1]; 79 ay = &a[l * n + 1]; 80 for ( ll=0; ll<n; ll++ ) { 81 tmp = ax[ll]; 82 ax[ll] = ay[ll]; 83 ay[ll] = tmp; 84 } 85 } 86 } 87 PetscFunctionReturn(0); 88 } 89 90