libflame
revision_anchor
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Functions | |
int | chetd2_fla (char *uplo, integer *n, complex *a, integer *lda, real *d__, real *e, complex *tau, integer *info) |
int chetd2_fla | ( | char * | uplo, |
integer * | n, | ||
complex * | a, | ||
integer * | lda, | ||
real * | d__, | ||
real * | e, | ||
complex * | tau, | ||
integer * | info | ||
) |
References complex::i, and complex::r.
Referenced by chetrd_fla().
{ /* System generated locals */ integer a_dim1, a_offset, i__1, i__2, i__3; real r__1; complex q__1, q__2, q__3, q__4; /* Local variables */ integer i__; complex taui; extern /* Subroutine */ int cher2_(char *, integer *, complex *, complex * , integer *, complex *, integer *, complex *, integer *); complex alpha; extern /* Complex */ VOID cdotc_f2c_(complex *, integer *, complex *, integer *, complex *, integer *); extern logical lsame_(char *, char *); extern /* Subroutine */ int chemv_(char *, integer *, complex *, complex * , integer *, complex *, integer *, complex *, complex *, integer * ), caxpy_(integer *, complex *, complex *, integer *, complex *, integer *); logical upper; extern /* Subroutine */ int clarfg_(integer *, complex *, complex *, integer *, complex *), xerbla_(char *, integer *); /* -- LAPACK computational routine (version 3.4.2) -- */ /* -- LAPACK is a software package provided by Univ. of Tennessee, -- */ /* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */ /* September 2012 */ /* .. Scalar Arguments .. */ /* .. */ /* .. Array Arguments .. */ /* .. */ /* ===================================================================== */ /* .. Parameters .. */ /* .. */ /* .. Local Scalars .. */ /* .. */ /* .. External Subroutines .. */ /* .. */ /* .. External Functions .. */ /* .. */ /* .. Intrinsic Functions .. */ /* .. */ /* .. Executable Statements .. */ /* Test the input parameters */ /* Parameter adjustments */ a_dim1 = *lda; a_offset = 1 + a_dim1; a -= a_offset; --d__; --e; --tau; /* Function Body */ *info = 0; upper = lsame_(uplo, "U"); if (! upper && ! lsame_(uplo, "L")) { *info = -1; } else if (*n < 0) { *info = -2; } else if (*lda < max(1,*n)) { *info = -4; } if (*info != 0) { i__1 = -(*info); xerbla_("CHETD2", &i__1); return 0; } /* Quick return if possible */ if (*n <= 0) { return 0; } if (upper) { /* Reduce the upper triangle of A */ i__1 = *n + *n * a_dim1; i__2 = *n + *n * a_dim1; r__1 = a[i__2].r; a[i__1].r = r__1; a[i__1].i = 0.f; // , expr subst for (i__ = *n - 1; i__ >= 1; --i__) { /* Generate elementary reflector H(i) = I - tau * v * v**H */ /* to annihilate A(1:i-1,i+1) */ i__1 = i__ + (i__ + 1) * a_dim1; alpha.r = a[i__1].r; alpha.i = a[i__1].i; // , expr subst clarfg_(&i__, &alpha, &a[(i__ + 1) * a_dim1 + 1], &c__1, &taui); i__1 = i__; e[i__1] = alpha.r; if (taui.r != 0.f || taui.i != 0.f) { /* Apply H(i) from both sides to A(1:i,1:i) */ i__1 = i__ + (i__ + 1) * a_dim1; a[i__1].r = 1.f; a[i__1].i = 0.f; // , expr subst /* Compute x := tau * A * v storing x in TAU(1:i) */ chemv_(uplo, &i__, &taui, &a[a_offset], lda, &a[(i__ + 1) * a_dim1 + 1], &c__1, &c_b2, &tau[1], &c__1); /* Compute w := x - 1/2 * tau * (x**H * v) * v */ q__3.r = -.5f; q__3.i = -0.f; // , expr subst q__2.r = q__3.r * taui.r - q__3.i * taui.i; q__2.i = q__3.r * taui.i + q__3.i * taui.r; // , expr subst cdotc_f2c_(&q__4, &i__, &tau[1], &c__1, &a[(i__ + 1) * a_dim1 + 1] , &c__1); q__1.r = q__2.r * q__4.r - q__2.i * q__4.i; q__1.i = q__2.r * q__4.i + q__2.i * q__4.r; // , expr subst alpha.r = q__1.r; alpha.i = q__1.i; // , expr subst caxpy_(&i__, &alpha, &a[(i__ + 1) * a_dim1 + 1], &c__1, &tau[ 1], &c__1); /* Apply the transformation as a rank-2 update: */ /* A := A - v * w**H - w * v**H */ q__1.r = -1.f; q__1.i = -0.f; // , expr subst cher2_(uplo, &i__, &q__1, &a[(i__ + 1) * a_dim1 + 1], &c__1, & tau[1], &c__1, &a[a_offset], lda); } else { i__1 = i__ + i__ * a_dim1; i__2 = i__ + i__ * a_dim1; r__1 = a[i__2].r; a[i__1].r = r__1; a[i__1].i = 0.f; // , expr subst } i__1 = i__ + (i__ + 1) * a_dim1; i__2 = i__; a[i__1].r = e[i__2]; a[i__1].i = 0.f; // , expr subst i__1 = i__ + 1; i__2 = i__ + 1 + (i__ + 1) * a_dim1; d__[i__1] = a[i__2].r; i__1 = i__; tau[i__1].r = taui.r; tau[i__1].i = taui.i; // , expr subst /* L10: */ } i__1 = a_dim1 + 1; d__[1] = a[i__1].r; } else { /* Reduce the lower triangle of A */ i__1 = a_dim1 + 1; i__2 = a_dim1 + 1; r__1 = a[i__2].r; a[i__1].r = r__1; a[i__1].i = 0.f; // , expr subst i__1 = *n - 1; for (i__ = 1; i__ <= i__1; ++i__) { /* Generate elementary reflector H(i) = I - tau * v * v**H */ /* to annihilate A(i+2:n,i) */ i__2 = i__ + 1 + i__ * a_dim1; alpha.r = a[i__2].r; alpha.i = a[i__2].i; // , expr subst i__2 = *n - i__; /* Computing MIN */ i__3 = i__ + 2; clarfg_(&i__2, &alpha, &a[min(i__3,*n) + i__ * a_dim1], &c__1, & taui); i__2 = i__; e[i__2] = alpha.r; if (taui.r != 0.f || taui.i != 0.f) { /* Apply H(i) from both sides to A(i+1:n,i+1:n) */ i__2 = i__ + 1 + i__ * a_dim1; a[i__2].r = 1.f; a[i__2].i = 0.f; // , expr subst /* Compute x := tau * A * v storing y in TAU(i:n-1) */ i__2 = *n - i__; chemv_(uplo, &i__2, &taui, &a[i__ + 1 + (i__ + 1) * a_dim1], lda, &a[i__ + 1 + i__ * a_dim1], &c__1, &c_b2, &tau[ i__], &c__1); /* Compute w := x - 1/2 * tau * (x**H * v) * v */ q__3.r = -.5f; q__3.i = -0.f; // , expr subst q__2.r = q__3.r * taui.r - q__3.i * taui.i; q__2.i = q__3.r * taui.i + q__3.i * taui.r; // , expr subst i__2 = *n - i__; cdotc_f2c_(&q__4, &i__2, &tau[i__], &c__1, &a[i__ + 1 + i__ * a_dim1], &c__1); q__1.r = q__2.r * q__4.r - q__2.i * q__4.i; q__1.i = q__2.r * q__4.i + q__2.i * q__4.r; // , expr subst alpha.r = q__1.r; alpha.i = q__1.i; // , expr subst i__2 = *n - i__; caxpy_(&i__2, &alpha, &a[i__ + 1 + i__ * a_dim1], &c__1, &tau[ i__], &c__1); /* Apply the transformation as a rank-2 update: */ /* A := A - v * w**H - w * v**H */ i__2 = *n - i__; q__1.r = -1.f; q__1.i = -0.f; // , expr subst cher2_(uplo, &i__2, &q__1, &a[i__ + 1 + i__ * a_dim1], &c__1, &tau[i__], &c__1, &a[i__ + 1 + (i__ + 1) * a_dim1], lda); } else { i__2 = i__ + 1 + (i__ + 1) * a_dim1; i__3 = i__ + 1 + (i__ + 1) * a_dim1; r__1 = a[i__3].r; a[i__2].r = r__1; a[i__2].i = 0.f; // , expr subst } i__2 = i__ + 1 + i__ * a_dim1; i__3 = i__; a[i__2].r = e[i__3]; a[i__2].i = 0.f; // , expr subst i__2 = i__; i__3 = i__ + i__ * a_dim1; d__[i__2] = a[i__3].r; i__2 = i__; tau[i__2].r = taui.r; tau[i__2].i = taui.i; // , expr subst /* L20: */ } i__1 = *n; i__2 = *n + *n * a_dim1; d__[i__1] = a[i__2].r; } return 0; /* End of CHETD2 */ }