#include "blaswrap.h" /* -- translated by f2c (version 19990503). You must link the resulting object file with the libraries: -lf2c -lm (in that order) */ #include "f2c.h" /* Table of constant values */ static integer c__1 = 1; /* Subroutine */ int ctpt05_(char *uplo, char *trans, char *diag, integer *n, integer *nrhs, complex *ap, complex *b, integer *ldb, complex *x, integer *ldx, complex *xact, integer *ldxact, real *ferr, real *berr, real *reslts) { /* System generated locals */ integer b_dim1, b_offset, x_dim1, x_offset, xact_dim1, xact_offset, i__1, i__2, i__3, i__4, i__5; real r__1, r__2, r__3, r__4; complex q__1, q__2; /* Builtin functions */ double r_imag(complex *); /* Local variables */ static real diff, axbi; static integer imax; static real unfl, ovfl; static logical unit; static integer i__, j, k; extern logical lsame_(char *, char *); static logical upper; static real xnorm; static integer jc; extern integer icamax_(integer *, complex *, integer *); extern doublereal slamch_(char *); static real errbnd; static logical notran; static integer ifu; static real eps, tmp; #define xact_subscr(a_1,a_2) (a_2)*xact_dim1 + a_1 #define xact_ref(a_1,a_2) xact[xact_subscr(a_1,a_2)] #define b_subscr(a_1,a_2) (a_2)*b_dim1 + a_1 #define b_ref(a_1,a_2) b[b_subscr(a_1,a_2)] #define x_subscr(a_1,a_2) (a_2)*x_dim1 + a_1 #define x_ref(a_1,a_2) x[x_subscr(a_1,a_2)] /* -- LAPACK test routine (version 3.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University February 29, 1992 Purpose ======= CTPT05 tests the error bounds from iterative refinement for the computed solution to a system of equations A*X = B, where A is a triangular matrix in packed storage format. RESLTS(1) = test of the error bound = norm(X - XACT) / ( norm(X) * FERR ) A large value is returned if this ratio is not less than one. RESLTS(2) = residual from the iterative refinement routine = the maximum of BERR / ( (n+1)*EPS + (*) ), where (*) = (n+1)*UNFL / (min_i (abs(A)*abs(X) +abs(b))_i ) Arguments ========= UPLO (input) CHARACTER*1 Specifies whether the matrix A is upper or lower triangular. = 'U': Upper triangular = 'L': Lower triangular TRANS (input) CHARACTER*1 Specifies the form of the system of equations. = 'N': A * X = B (No transpose) = 'T': A'* X = B (Transpose) = 'C': A'* X = B (Conjugate transpose = Transpose) DIAG (input) CHARACTER*1 Specifies whether or not the matrix A is unit triangular. = 'N': Non-unit triangular = 'U': Unit triangular N (input) INTEGER The number of rows of the matrices X, B, and XACT, and the order of the matrix A. N >= 0. NRHS (input) INTEGER The number of columns of the matrices X, B, and XACT. NRHS >= 0. AP (input) COMPLEX array, dimension (N*(N+1)/2) The upper or lower triangular matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. If DIAG = 'U', the diagonal elements of A are not referenced and are assumed to be 1. B (input) COMPLEX array, dimension (LDB,NRHS) The right hand side vectors for the system of linear equations. LDB (input) INTEGER The leading dimension of the array B. LDB >= max(1,N). X (input) COMPLEX array, dimension (LDX,NRHS) The computed solution vectors. Each vector is stored as a column of the matrix X. LDX (input) INTEGER The leading dimension of the array X. LDX >= max(1,N). XACT (input) COMPLEX array, dimension (LDX,NRHS) The exact solution vectors. Each vector is stored as a column of the matrix XACT. LDXACT (input) INTEGER The leading dimension of the array XACT. LDXACT >= max(1,N). FERR (input) REAL array, dimension (NRHS) The estimated forward error bounds for each solution vector X. If XTRUE is the true solution, FERR bounds the magnitude of the largest entry in (X - XTRUE) divided by the magnitude of the largest entry in X. BERR (input) REAL array, dimension (NRHS) The componentwise relative backward error of each solution vector (i.e., the smallest relative change in any entry of A or B that makes X an exact solution). RESLTS (output) REAL array, dimension (2) The maximum over the NRHS solution vectors of the ratios: RESLTS(1) = norm(X - XACT) / ( norm(X) * FERR ) RESLTS(2) = BERR / ( (n+1)*EPS + (*) ) ===================================================================== Quick exit if N = 0 or NRHS = 0. Parameter adjustments */ --ap; b_dim1 = *ldb; b_offset = 1 + b_dim1 * 1; b -= b_offset; x_dim1 = *ldx; x_offset = 1 + x_dim1 * 1; x -= x_offset; xact_dim1 = *ldxact; xact_offset = 1 + xact_dim1 * 1; xact -= xact_offset; --ferr; --berr; --reslts; /* Function Body */ if (*n <= 0 || *nrhs <= 0) { reslts[1] = 0.f; reslts[2] = 0.f; return 0; } eps = slamch_("Epsilon"); unfl = slamch_("Safe minimum"); ovfl = 1.f / unfl; upper = lsame_(uplo, "U"); notran = lsame_(trans, "N"); unit = lsame_(diag, "U"); /* Test 1: Compute the maximum of norm(X - XACT) / ( norm(X) * FERR ) over all the vectors X and XACT using the infinity-norm. */ errbnd = 0.f; i__1 = *nrhs; for (j = 1; j <= i__1; ++j) { imax = icamax_(n, &x_ref(1, j), &c__1); /* Computing MAX */ i__2 = x_subscr(imax, j); r__3 = (r__1 = x[i__2].r, dabs(r__1)) + (r__2 = r_imag(&x_ref(imax, j) ), dabs(r__2)); xnorm = dmax(r__3,unfl); diff = 0.f; i__2 = *n; for (i__ = 1; i__ <= i__2; ++i__) { i__3 = x_subscr(i__, j); i__4 = xact_subscr(i__, j); q__2.r = x[i__3].r - xact[i__4].r, q__2.i = x[i__3].i - xact[i__4] .i; q__1.r = q__2.r, q__1.i = q__2.i; /* Computing MAX */ r__3 = diff, r__4 = (r__1 = q__1.r, dabs(r__1)) + (r__2 = r_imag(& q__1), dabs(r__2)); diff = dmax(r__3,r__4); /* L10: */ } if (xnorm > 1.f) { goto L20; } else if (diff <= ovfl * xnorm) { goto L20; } else { errbnd = 1.f / eps; goto L30; } L20: if (diff / xnorm <= ferr[j]) { /* Computing MAX */ r__1 = errbnd, r__2 = diff / xnorm / ferr[j]; errbnd = dmax(r__1,r__2); } else { errbnd = 1.f / eps; } L30: ; } reslts[1] = errbnd; /* Test 2: Compute the maximum of BERR / ( (n+1)*EPS + (*) ), where (*) = (n+1)*UNFL / (min_i (abs(A)*abs(X) +abs(b))_i ) */ ifu = 0; if (unit) { ifu = 1; } i__1 = *nrhs; for (k = 1; k <= i__1; ++k) { i__2 = *n; for (i__ = 1; i__ <= i__2; ++i__) { i__3 = b_subscr(i__, k); tmp = (r__1 = b[i__3].r, dabs(r__1)) + (r__2 = r_imag(&b_ref(i__, k)), dabs(r__2)); if (upper) { jc = (i__ - 1) * i__ / 2; if (! notran) { i__3 = i__ - ifu; for (j = 1; j <= i__3; ++j) { i__4 = jc + j; i__5 = x_subscr(j, k); tmp += ((r__1 = ap[i__4].r, dabs(r__1)) + (r__2 = r_imag(&ap[jc + j]), dabs(r__2))) * ((r__3 = x[i__5].r, dabs(r__3)) + (r__4 = r_imag(& x_ref(j, k)), dabs(r__4))); /* L40: */ } if (unit) { i__3 = x_subscr(i__, k); tmp += (r__1 = x[i__3].r, dabs(r__1)) + (r__2 = r_imag(&x_ref(i__, k)), dabs(r__2)); } } else { jc += i__; if (unit) { i__3 = x_subscr(i__, k); tmp += (r__1 = x[i__3].r, dabs(r__1)) + (r__2 = r_imag(&x_ref(i__, k)), dabs(r__2)); jc += i__; } i__3 = *n; for (j = i__ + ifu; j <= i__3; ++j) { i__4 = jc; i__5 = x_subscr(j, k); tmp += ((r__1 = ap[i__4].r, dabs(r__1)) + (r__2 = r_imag(&ap[jc]), dabs(r__2))) * ((r__3 = x[ i__5].r, dabs(r__3)) + (r__4 = r_imag(&x_ref( j, k)), dabs(r__4))); jc += j; /* L50: */ } } } else { if (notran) { jc = i__; i__3 = i__ - ifu; for (j = 1; j <= i__3; ++j) { i__4 = jc; i__5 = x_subscr(j, k); tmp += ((r__1 = ap[i__4].r, dabs(r__1)) + (r__2 = r_imag(&ap[jc]), dabs(r__2))) * ((r__3 = x[ i__5].r, dabs(r__3)) + (r__4 = r_imag(&x_ref( j, k)), dabs(r__4))); jc = jc + *n - j; /* L60: */ } if (unit) { i__3 = x_subscr(i__, k); tmp += (r__1 = x[i__3].r, dabs(r__1)) + (r__2 = r_imag(&x_ref(i__, k)), dabs(r__2)); } } else { jc = (i__ - 1) * (*n - i__) + i__ * (i__ + 1) / 2; if (unit) { i__3 = x_subscr(i__, k); tmp += (r__1 = x[i__3].r, dabs(r__1)) + (r__2 = r_imag(&x_ref(i__, k)), dabs(r__2)); } i__3 = *n; for (j = i__ + ifu; j <= i__3; ++j) { i__4 = jc + j - i__; i__5 = x_subscr(j, k); tmp += ((r__1 = ap[i__4].r, dabs(r__1)) + (r__2 = r_imag(&ap[jc + j - i__]), dabs(r__2))) * (( r__3 = x[i__5].r, dabs(r__3)) + (r__4 = r_imag(&x_ref(j, k)), dabs(r__4))); /* L70: */ } } } if (i__ == 1) { axbi = tmp; } else { axbi = dmin(axbi,tmp); } /* L80: */ } /* Computing MAX */ r__1 = axbi, r__2 = (*n + 1) * unfl; tmp = berr[k] / ((*n + 1) * eps + (*n + 1) * unfl / dmax(r__1,r__2)); if (k == 1) { reslts[2] = tmp; } else { reslts[2] = dmax(reslts[2],tmp); } /* L90: */ } return 0; /* End of CTPT05 */ } /* ctpt05_ */ #undef x_ref #undef x_subscr #undef b_ref #undef b_subscr #undef xact_ref #undef xact_subscr .