1 #ifndef lint 2 static char vcid[] = "$Id: dgedi.c,v 1.4 1996/12/18 00:01:36 balay Exp balay $"; 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,jn; 21 Scalar t, *aa,*ax,*ay,tmp; 22 23 --work; 24 --ipvt; 25 a -= n + 1; 26 27 /* compute inverse(u) */ 28 29 for (k = 1; k <= n; ++k) { 30 kn = k*n; 31 knp1 = kn + k; 32 a[knp1] = 1.0 / a[knp1]; 33 t = -a[knp1]; 34 i__2 = k - 1; 35 aa = &a[1 + kn]; 36 for ( ll=0; ll<i__2; ll++ ) aa[ll] *= t; 37 kp1 = k + 1; 38 if (n < kp1) continue; 39 ax = aa; 40 for (j = kp1; j <= n; ++j) { 41 jn = j*n; 42 t = a[k + jn]; 43 a[k + jn] = 0.; 44 ay = &a[1 + jn]; 45 for ( ll=0; ll<k; ll++ ) { 46 ay[ll] += t*ax[ll]; 47 } 48 } 49 } 50 51 /* form inverse(u)*inverse(l) */ 52 53 nm1 = n - 1; 54 if (nm1 < 1) { 55 return 0; 56 } 57 for (kb = 1; kb <= nm1; ++kb) { 58 k = n - kb; 59 kn = k*n; 60 kp1 = k + 1; 61 aa = a + kn; 62 for (i = kp1; i <= n; ++i) { 63 work[i] = aa[i]; 64 aa[i] = 0.; 65 } 66 for (j = kp1; j <= n; ++j) { 67 t = work[j]; 68 ax = &a[j * n + 1]; 69 ay = &a[kn + 1]; 70 for ( ll=0; ll<n; ll++ ) { 71 ay[ll] += t*ax[ll]; 72 } 73 } 74 l = ipvt[k]; 75 if (l != k) { 76 ax = &a[kn + 1]; 77 ay = &a[l * n + 1]; 78 for ( ll=0; ll<n; ll++ ) { 79 tmp = ax[ll]; 80 ax[ll] = ay[ll]; 81 ay[ll] = tmp; 82 } 83 } 84 } 85 return 0; 86 } 87 88