INTEGER FUNCTION IZMAX1( N, CX, INCX ) * * -- LAPACK auxiliary routine (version 3.2) -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * November 2006 * * .. Scalar Arguments .. INTEGER INCX, N * .. * .. Array Arguments .. COMPLEX*16 CX( * ) * .. * * Purpose * ======= * * IZMAX1 finds the index of the element whose real part has maximum * absolute value. * * Based on IZAMAX from Level 1 BLAS. * The change is to use the 'genuine' absolute value. * * Contributed by Nick Higham for use with ZLACON. * * Arguments * ========= * * N (input) INTEGER * The number of elements in the vector CX. * * CX (input) COMPLEX*16 array, dimension (N) * The vector whose elements will be summed. * * INCX (input) INTEGER * The spacing between successive values of CX. INCX >= 1. * * ===================================================================== * * .. Local Scalars .. INTEGER I, IX DOUBLE PRECISION SMAX COMPLEX*16 ZDUM * .. * .. Intrinsic Functions .. INTRINSIC ABS * .. * .. Statement Functions .. DOUBLE PRECISION CABS1 * .. * .. Statement Function definitions .. * * NEXT LINE IS THE ONLY MODIFICATION. CABS1( ZDUM ) = ABS( ZDUM ) * .. * .. Executable Statements .. * IZMAX1 = 0 IF( N.LT.1 ) \$ RETURN IZMAX1 = 1 IF( N.EQ.1 ) \$ RETURN IF( INCX.EQ.1 ) \$ GO TO 30 * * CODE FOR INCREMENT NOT EQUAL TO 1 * IX = 1 SMAX = CABS1( CX( 1 ) ) IX = IX + INCX DO 20 I = 2, N IF( CABS1( CX( IX ) ).LE.SMAX ) \$ GO TO 10 IZMAX1 = I SMAX = CABS1( CX( IX ) ) 10 CONTINUE IX = IX + INCX 20 CONTINUE RETURN * * CODE FOR INCREMENT EQUAL TO 1 * 30 CONTINUE SMAX = CABS1( CX( 1 ) ) DO 40 I = 2, N IF( CABS1( CX( I ) ).LE.SMAX ) \$ GO TO 40 IZMAX1 = I SMAX = CABS1( CX( I ) ) 40 CONTINUE RETURN * * End of IZMAX1 * END