• NAME
• SYNOPSIS
• F95 INTERFACE
• C INTERFACE
• PURPOSE
• ARGUMENTS
• NOTES

NAME

izamax - return the index of the element with largest absolute value.

SYNOPSIS

  INTEGER FUNCTION IZAMAX( N, X, INCX)
  DOUBLE COMPLEX X(*)
  INTEGER N, INCX

  INTEGER*8 FUNCTION IZAMAX_64( N, X, INCX)
  DOUBLE COMPLEX X(*)
  INTEGER*8 N, INCX

F95 INTERFACE

  INTEGER FUNCTION IAMAX( [N], X, [INCX])
  COMPLEX(8), DIMENSION(:) :: X
  INTEGER :: N, INCX

  INTEGER(8) FUNCTION IAMAX_64( [N], X, [INCX])
  COMPLEX(8), DIMENSION(:) :: X
  INTEGER(8) :: N, INCX

C INTERFACE

#include <sunperf.h>

int izamax(int n, doublecomplex *x, int incx);

long izamax_64(long n, doublecomplex *x, long incx);

PURPOSE

izamax return the index of the element in x with largest absolute value where x is an n-vector and absolute value is defined as the sum of the absolute value of the real part and the absolute value of the imaginary part.

ARGUMENTS

• N (input)
  On entry, N specifies the number of elements in the vector. N must be at least one for the subroutine to have any visible effect. Unchanged on exit.

• X (input)
  ( 1 + ( n - 1 )*abs( INCX ) ). On entry, the incremented array X must contain the vector x. Unchanged on exit.

• INCX (input)
  On entry, INCX specifies the increment for the elements of X. INCX must be positive. Unchanged on exit.

NOTES

If the vector contains all NaNs, the function returns 1. If the vector contains valid double complex numbers and one or more NaNs, the routine returns the index of the element containing the largest absolute value.