1be1d678aSKris Buschelman 26d84be18SBarry Smith /* 36d84be18SBarry Smith This file creating by running f2c 46d84be18SBarry Smith linpack. this version dated 08/14/78 56d84be18SBarry Smith cleve moler, university of new mexico, argonne national lab. 66d84be18SBarry Smith 76d84be18SBarry Smith Computes the inverse of a matrix given its factors and pivots 896b95a6bSBarry Smith calculated by PetscLINPACKgefa(). Performed in-place for an n by n 99d8b60e5SBarry Smith dense matrix. 109d8b60e5SBarry Smith 119d8b60e5SBarry Smith Used by the sparse factorization routines in 12dd882469SBarry Smith src/mat/impls/baij/seq 1371c5468dSBarry Smith 142bb67c89SBarry Smith */ 152bb67c89SBarry Smith 16c6db04a5SJed Brown #include <petscsys.h> 17*5f748d31SJed Brown #include <petsc/private/kernels/blockinvert.h> 182bb67c89SBarry Smith 19*5f748d31SJed Brown PetscErrorCode PetscLINPACKgedi(MatScalar *a,PetscInt n,PetscInt *ipvt,MatScalar *work) 202bb67c89SBarry Smith { 21690b6cddSBarry Smith PetscInt i__2,kb,kp1,nm1,i,j,k,l,ll,kn,knp1,jn1; 223f1db9ecSBarry Smith MatScalar *aa,*ax,*ay,tmp; 233f1db9ecSBarry Smith MatScalar t; 242bb67c89SBarry Smith 253a40ed3dSBarry Smith PetscFunctionBegin; 266d84be18SBarry Smith --work; 276d84be18SBarry Smith --ipvt; 2839d66777SBarry Smith a -= n + 1; 292bb67c89SBarry Smith 302bb67c89SBarry Smith /* compute inverse(u) */ 312bb67c89SBarry Smith 326d84be18SBarry Smith for (k = 1; k <= n; ++k) { 3339d66777SBarry Smith kn = k*n; 3439d66777SBarry Smith knp1 = kn + k; 3539d66777SBarry Smith a[knp1] = 1.0 / a[knp1]; 3639d66777SBarry Smith t = -a[knp1]; 372bb67c89SBarry Smith i__2 = k - 1; 3839d66777SBarry Smith aa = &a[1 + kn]; 396d84be18SBarry Smith for (ll=0; ll<i__2; ll++) aa[ll] *= t; 402bb67c89SBarry Smith kp1 = k + 1; 416d84be18SBarry Smith if (n < kp1) continue; 426d84be18SBarry Smith ax = aa; 436d84be18SBarry Smith for (j = kp1; j <= n; ++j) { 448d3e6ddaSBarry Smith jn1 = j*n; 458d3e6ddaSBarry Smith t = a[k + jn1]; 468d3e6ddaSBarry Smith a[k + jn1] = 0.; 478d3e6ddaSBarry Smith ay = &a[1 + jn1]; 4826fbe8dcSKarl Rupp for (ll=0; ll<k; ll++) ay[ll] += t*ax[ll]; 492bb67c89SBarry Smith } 502bb67c89SBarry Smith } 512bb67c89SBarry Smith 522bb67c89SBarry Smith /* form inverse(u)*inverse(l) */ 532bb67c89SBarry Smith 546d84be18SBarry Smith nm1 = n - 1; 552bb67c89SBarry Smith if (nm1 < 1) { 563a40ed3dSBarry Smith PetscFunctionReturn(0); 572bb67c89SBarry Smith } 586d84be18SBarry Smith for (kb = 1; kb <= nm1; ++kb) { 596d84be18SBarry Smith k = n - kb; 6039d66777SBarry Smith kn = k*n; 612bb67c89SBarry Smith kp1 = k + 1; 6239d66777SBarry Smith aa = a + kn; 636d84be18SBarry Smith for (i = kp1; i <= n; ++i) { 646d84be18SBarry Smith work[i] = aa[i]; 656d84be18SBarry Smith aa[i] = 0.; 662bb67c89SBarry Smith } 676d84be18SBarry Smith for (j = kp1; j <= n; ++j) { 682bb67c89SBarry Smith t = work[j]; 696d84be18SBarry Smith ax = &a[j * n + 1]; 7039d66777SBarry Smith ay = &a[kn + 1]; 7126fbe8dcSKarl Rupp for (ll=0; ll<n; ll++) ay[ll] += t*ax[ll]; 722bb67c89SBarry Smith } 732bb67c89SBarry Smith l = ipvt[k]; 742bb67c89SBarry Smith if (l != k) { 7539d66777SBarry Smith ax = &a[kn + 1]; 766d84be18SBarry Smith ay = &a[l * n + 1]; 776d84be18SBarry Smith for (ll=0; ll<n; ll++) { 786d84be18SBarry Smith tmp = ax[ll]; 796d84be18SBarry Smith ax[ll] = ay[ll]; 806d84be18SBarry Smith ay[ll] = tmp; 812bb67c89SBarry Smith } 822bb67c89SBarry Smith } 836d84be18SBarry Smith } 843a40ed3dSBarry Smith PetscFunctionReturn(0); 856d84be18SBarry Smith } 862bb67c89SBarry Smith 87