#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int zdrscl_(integer *n, doublereal *sa, doublecomplex *sx, integer *incx) { /* -- LAPACK auxiliary routine (version 3.1) -- Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. November 2006 Purpose ======= ZDRSCL multiplies an n-element complex vector x by the real scalar 1/a. This is done without overflow or underflow as long as the final result x/a does not overflow or underflow. Arguments ========= N (input) INTEGER The number of components of the vector x. SA (input) DOUBLE PRECISION The scalar a which is used to divide each component of x. SA must be >= 0, or the subroutine will divide by zero. SX (input/output) COMPLEX*16 array, dimension (1+(N-1)*abs(INCX)) The n-element vector x. INCX (input) INTEGER The increment between successive values of the vector SX. > 0: SX(1) = X(1) and SX(1+(i-1)*INCX) = x(i), 1< i<= n ===================================================================== Quick return if possible Parameter adjustments */ static doublereal mul, cden; static logical done; static doublereal cnum, cden1, cnum1; extern /* Subroutine */ int dlabad_(doublereal *, doublereal *); extern doublereal dlamch_(char *); extern /* Subroutine */ int zdscal_(integer *, doublereal *, doublecomplex *, integer *); static doublereal bignum, smlnum; --sx; /* Function Body */ if (*n <= 0) { return 0; } /* Get machine parameters */ smlnum = dlamch_("S"); bignum = 1. / smlnum; dlabad_(&smlnum, &bignum); /* Initialize the denominator to SA and the numerator to 1. */ cden = *sa; cnum = 1.; L10: cden1 = cden * smlnum; cnum1 = cnum / bignum; if (abs(cden1) > abs(cnum) && cnum != 0.) { /* Pre-multiply X by SMLNUM if CDEN is large compared to CNUM. */ mul = smlnum; done = FALSE_; cden = cden1; } else if (abs(cnum1) > abs(cden)) { /* Pre-multiply X by BIGNUM if CDEN is small compared to CNUM. */ mul = bignum; done = FALSE_; cnum = cnum1; } else { /* Multiply X by CNUM / CDEN and return. */ mul = cnum / cden; done = TRUE_; } /* Scale the vector X by MUL */ zdscal_(n, &mul, &sx[1], incx); if (! done) { goto L10; } return 0; /* End of ZDRSCL */ } /* zdrscl_ */