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239 lines
6.4 KiB
239 lines
6.4 KiB
/* dlansy.f -- translated by f2c (version 20061008). |
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You must link the resulting object file with libf2c: |
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on Microsoft Windows system, link with libf2c.lib; |
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm |
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or, if you install libf2c.a in a standard place, with -lf2c -lm |
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-- in that order, at the end of the command line, as in |
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cc *.o -lf2c -lm |
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g., |
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http://www.netlib.org/f2c/libf2c.zip |
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*/ |
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#include "clapack.h" |
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/* Table of constant values */ |
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static integer c__1 = 1; |
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doublereal dlansy_(char *norm, char *uplo, integer *n, doublereal *a, integer |
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*lda, doublereal *work) |
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{ |
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/* System generated locals */ |
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integer a_dim1, a_offset, i__1, i__2; |
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doublereal ret_val, d__1, d__2, d__3; |
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/* Builtin functions */ |
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double sqrt(doublereal); |
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/* Local variables */ |
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integer i__, j; |
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doublereal sum, absa, scale; |
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extern logical lsame_(char *, char *); |
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doublereal value; |
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extern /* Subroutine */ int dlassq_(integer *, doublereal *, integer *, |
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doublereal *, doublereal *); |
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/* -- LAPACK auxiliary routine (version 3.2) -- */ |
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/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ |
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/* November 2006 */ |
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/* .. Scalar Arguments .. */ |
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/* .. */ |
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/* .. Array Arguments .. */ |
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/* .. */ |
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/* Purpose */ |
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/* ======= */ |
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/* DLANSY returns the value of the one norm, or the Frobenius norm, or */ |
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/* the infinity norm, or the element of largest absolute value of a */ |
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/* real symmetric matrix A. */ |
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/* Description */ |
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/* =========== */ |
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/* DLANSY returns the value */ |
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/* DLANSY = ( max(abs(A(i,j))), NORM = 'M' or 'm' */ |
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/* ( */ |
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/* ( norm1(A), NORM = '1', 'O' or 'o' */ |
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/* ( */ |
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/* ( normI(A), NORM = 'I' or 'i' */ |
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/* ( */ |
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/* ( normF(A), NORM = 'F', 'f', 'E' or 'e' */ |
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/* where norm1 denotes the one norm of a matrix (maximum column sum), */ |
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/* normI denotes the infinity norm of a matrix (maximum row sum) and */ |
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/* normF denotes the Frobenius norm of a matrix (square root of sum of */ |
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/* squares). Note that max(abs(A(i,j))) is not a consistent matrix norm. */ |
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/* Arguments */ |
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/* ========= */ |
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/* NORM (input) CHARACTER*1 */ |
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/* Specifies the value to be returned in DLANSY as described */ |
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/* above. */ |
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/* UPLO (input) CHARACTER*1 */ |
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/* Specifies whether the upper or lower triangular part of the */ |
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/* symmetric matrix A is to be referenced. */ |
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/* = 'U': Upper triangular part of A is referenced */ |
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/* = 'L': Lower triangular part of A is referenced */ |
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/* N (input) INTEGER */ |
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/* The order of the matrix A. N >= 0. When N = 0, DLANSY is */ |
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/* set to zero. */ |
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/* A (input) DOUBLE PRECISION array, dimension (LDA,N) */ |
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/* The symmetric matrix A. If UPLO = 'U', the leading n by n */ |
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/* upper triangular part of A contains the upper triangular part */ |
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/* of the matrix A, and the strictly lower triangular part of A */ |
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/* is not referenced. If UPLO = 'L', the leading n by n lower */ |
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/* triangular part of A contains the lower triangular part of */ |
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/* the matrix A, and the strictly upper triangular part of A is */ |
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/* not referenced. */ |
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/* LDA (input) INTEGER */ |
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/* The leading dimension of the array A. LDA >= max(N,1). */ |
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/* WORK (workspace) DOUBLE PRECISION array, dimension (MAX(1,LWORK)), */ |
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/* where LWORK >= N when NORM = 'I' or '1' or 'O'; otherwise, */ |
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/* WORK is not referenced. */ |
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/* ===================================================================== */ |
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/* .. Parameters .. */ |
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/* .. */ |
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/* .. Local Scalars .. */ |
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/* .. */ |
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/* .. External Subroutines .. */ |
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/* .. */ |
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/* .. External Functions .. */ |
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/* .. */ |
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/* .. Intrinsic Functions .. */ |
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/* .. */ |
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/* .. Executable Statements .. */ |
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/* Parameter adjustments */ |
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a_dim1 = *lda; |
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a_offset = 1 + a_dim1; |
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a -= a_offset; |
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--work; |
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/* Function Body */ |
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if (*n == 0) { |
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value = 0.; |
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} else if (lsame_(norm, "M")) { |
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/* Find max(abs(A(i,j))). */ |
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value = 0.; |
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if (lsame_(uplo, "U")) { |
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i__1 = *n; |
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for (j = 1; j <= i__1; ++j) { |
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i__2 = j; |
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for (i__ = 1; i__ <= i__2; ++i__) { |
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/* Computing MAX */ |
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d__2 = value, d__3 = (d__1 = a[i__ + j * a_dim1], abs( |
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d__1)); |
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value = max(d__2,d__3); |
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/* L10: */ |
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} |
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/* L20: */ |
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} |
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} else { |
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i__1 = *n; |
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for (j = 1; j <= i__1; ++j) { |
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i__2 = *n; |
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for (i__ = j; i__ <= i__2; ++i__) { |
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/* Computing MAX */ |
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d__2 = value, d__3 = (d__1 = a[i__ + j * a_dim1], abs( |
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d__1)); |
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value = max(d__2,d__3); |
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/* L30: */ |
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} |
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/* L40: */ |
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} |
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} |
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} else if (lsame_(norm, "I") || lsame_(norm, "O") || *(unsigned char *)norm == '1') { |
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/* Find normI(A) ( = norm1(A), since A is symmetric). */ |
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value = 0.; |
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if (lsame_(uplo, "U")) { |
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i__1 = *n; |
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for (j = 1; j <= i__1; ++j) { |
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sum = 0.; |
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i__2 = j - 1; |
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for (i__ = 1; i__ <= i__2; ++i__) { |
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absa = (d__1 = a[i__ + j * a_dim1], abs(d__1)); |
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sum += absa; |
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work[i__] += absa; |
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/* L50: */ |
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} |
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work[j] = sum + (d__1 = a[j + j * a_dim1], abs(d__1)); |
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/* L60: */ |
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} |
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i__1 = *n; |
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for (i__ = 1; i__ <= i__1; ++i__) { |
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/* Computing MAX */ |
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d__1 = value, d__2 = work[i__]; |
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value = max(d__1,d__2); |
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/* L70: */ |
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} |
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} else { |
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i__1 = *n; |
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for (i__ = 1; i__ <= i__1; ++i__) { |
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work[i__] = 0.; |
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/* L80: */ |
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} |
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i__1 = *n; |
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for (j = 1; j <= i__1; ++j) { |
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sum = work[j] + (d__1 = a[j + j * a_dim1], abs(d__1)); |
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i__2 = *n; |
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for (i__ = j + 1; i__ <= i__2; ++i__) { |
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absa = (d__1 = a[i__ + j * a_dim1], abs(d__1)); |
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sum += absa; |
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work[i__] += absa; |
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/* L90: */ |
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} |
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value = max(value,sum); |
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/* L100: */ |
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} |
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} |
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} else if (lsame_(norm, "F") || lsame_(norm, "E")) { |
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/* Find normF(A). */ |
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scale = 0.; |
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sum = 1.; |
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if (lsame_(uplo, "U")) { |
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i__1 = *n; |
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for (j = 2; j <= i__1; ++j) { |
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i__2 = j - 1; |
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dlassq_(&i__2, &a[j * a_dim1 + 1], &c__1, &scale, &sum); |
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/* L110: */ |
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} |
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} else { |
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i__1 = *n - 1; |
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for (j = 1; j <= i__1; ++j) { |
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i__2 = *n - j; |
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dlassq_(&i__2, &a[j + 1 + j * a_dim1], &c__1, &scale, &sum); |
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/* L120: */ |
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} |
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} |
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sum *= 2; |
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i__1 = *lda + 1; |
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dlassq_(n, &a[a_offset], &i__1, &scale, &sum); |
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value = scale * sqrt(sum); |
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} |
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ret_val = value; |
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return ret_val; |
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/* End of DLANSY */ |
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} /* dlansy_ */
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