1a5eb4965SSatish Balay #ifdef PETSC_RCS_HEADER 2*3f1db9ecSBarry Smith static char vcid[] = "$Id: dgedi.c,v 1.8 1998/04/21 17:47:46 bsmith Exp bsmith $"; 36d84be18SBarry Smith #endif 46d84be18SBarry Smith 56d84be18SBarry Smith /* 66d84be18SBarry Smith This file creating by running f2c 76d84be18SBarry Smith linpack. this version dated 08/14/78 86d84be18SBarry Smith cleve moler, university of new mexico, argonne national lab. 96d84be18SBarry Smith 106d84be18SBarry Smith Computes the inverse of a matrix given its factors and pivots 116d84be18SBarry Smith calculated by Linpack_DGEFA(). 122bb67c89SBarry Smith */ 132bb67c89SBarry Smith 146d84be18SBarry Smith #include "petsc.h" 152bb67c89SBarry Smith 165615d1e5SSatish Balay #undef __FUNC__ 175615d1e5SSatish Balay #define __FUNC__ "Linpack_DGEDI" 18*3f1db9ecSBarry Smith int Linpack_DGEDI(MatScalar *a,int n,int *ipvt,MatScalar *work) 192bb67c89SBarry Smith { 208d3e6ddaSBarry Smith int i__2,kb, kp1, nm1,i, j, k, l, ll,kn,knp1,jn1; 21*3f1db9ecSBarry Smith MatScalar *aa,*ax,*ay,tmp; 22*3f1db9ecSBarry Smith MatScalar t; 232bb67c89SBarry Smith 243a40ed3dSBarry Smith PetscFunctionBegin; 256d84be18SBarry Smith --work; 266d84be18SBarry Smith --ipvt; 2739d66777SBarry Smith a -= n + 1; 282bb67c89SBarry Smith 292bb67c89SBarry Smith /* compute inverse(u) */ 302bb67c89SBarry Smith 316d84be18SBarry Smith for (k = 1; k <= n; ++k) { 3239d66777SBarry Smith kn = k*n; 3339d66777SBarry Smith knp1 = kn + k; 3439d66777SBarry Smith a[knp1] = 1.0 / a[knp1]; 3539d66777SBarry Smith t = -a[knp1]; 362bb67c89SBarry Smith i__2 = k - 1; 3739d66777SBarry Smith aa = &a[1 + kn]; 386d84be18SBarry Smith for ( ll=0; ll<i__2; ll++ ) aa[ll] *= t; 392bb67c89SBarry Smith kp1 = k + 1; 406d84be18SBarry Smith if (n < kp1) continue; 416d84be18SBarry Smith ax = aa; 426d84be18SBarry Smith for (j = kp1; j <= n; ++j) { 438d3e6ddaSBarry Smith jn1 = j*n; 448d3e6ddaSBarry Smith t = a[k + jn1]; 458d3e6ddaSBarry Smith a[k + jn1] = 0.; 468d3e6ddaSBarry Smith ay = &a[1 + jn1]; 476d84be18SBarry Smith for ( ll=0; ll<k; ll++ ) { 486d84be18SBarry Smith ay[ll] += t*ax[ll]; 492bb67c89SBarry Smith } 502bb67c89SBarry Smith } 512bb67c89SBarry Smith } 522bb67c89SBarry Smith 532bb67c89SBarry Smith /* form inverse(u)*inverse(l) */ 542bb67c89SBarry Smith 556d84be18SBarry Smith nm1 = n - 1; 562bb67c89SBarry Smith if (nm1 < 1) { 573a40ed3dSBarry Smith PetscFunctionReturn(0); 582bb67c89SBarry Smith } 596d84be18SBarry Smith for (kb = 1; kb <= nm1; ++kb) { 606d84be18SBarry Smith k = n - kb; 6139d66777SBarry Smith kn = k*n; 622bb67c89SBarry Smith kp1 = k + 1; 6339d66777SBarry Smith aa = a + kn; 646d84be18SBarry Smith for (i = kp1; i <= n; ++i) { 656d84be18SBarry Smith work[i] = aa[i]; 666d84be18SBarry Smith aa[i] = 0.; 672bb67c89SBarry Smith } 686d84be18SBarry Smith for (j = kp1; j <= n; ++j) { 692bb67c89SBarry Smith t = work[j]; 706d84be18SBarry Smith ax = &a[j * n + 1]; 7139d66777SBarry Smith ay = &a[kn + 1]; 726d84be18SBarry Smith for ( ll=0; ll<n; ll++ ) { 736d84be18SBarry Smith ay[ll] += t*ax[ll]; 746d84be18SBarry Smith } 752bb67c89SBarry Smith } 762bb67c89SBarry Smith l = ipvt[k]; 772bb67c89SBarry Smith if (l != k) { 7839d66777SBarry Smith ax = &a[kn + 1]; 796d84be18SBarry Smith ay = &a[l * n + 1]; 806d84be18SBarry Smith for ( ll=0; ll<n; ll++ ) { 816d84be18SBarry Smith tmp = ax[ll]; 826d84be18SBarry Smith ax[ll] = ay[ll]; 836d84be18SBarry Smith ay[ll] = tmp; 842bb67c89SBarry Smith } 852bb67c89SBarry Smith } 866d84be18SBarry Smith } 873a40ed3dSBarry Smith PetscFunctionReturn(0); 886d84be18SBarry Smith } 892bb67c89SBarry Smith 90