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

NAME

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

SYNOPSIS

  INTEGER FUNCTION IDAMAX( N, X, INCX)
  INTEGER N, INCX
  DOUBLE PRECISION X(*)

  INTEGER*8 FUNCTION IDAMAX_64( N, X, INCX)
  INTEGER*8 N, INCX
  DOUBLE PRECISION X(*)

F95 INTERFACE

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

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

C INTERFACE

#include <sunperf.h>

int idamax(int n, double *x, int incx);

long idamax_64(long n, double *x, long incx);

PURPOSE

idamax return the index of the element in x with largest absolute value where x is an n-vector.

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 floating point numbers and one or more NaNs, the routine returns the index of the lement containing the largest absolute value.