i?amax

Syntax

FORTRAN 77:

index = isamax(n, x, incx)

index = idamax(n, x, incx)

index = icamax(n, x, incx)

index = izamax(n, x, incx)

Fortran 95:

index = iamax(x)

Include Files

The FORTRAN 77 interfaces are specified in the mkl_blas.fi include file, the Fortran 95 interfaces are specified in the blas.f90 include file, and the C interfaces are specified in the mkl_blas.h include file.

Description

This function is declared in mkl_blas.fi for FORTRAN 77 interface, in blas.f90 for Fortran 95 interface, and in mkl_blas.h for C interface.

Given a vector x, the i?amax functions return the position of the vector element x(i) that has the largest absolute value for real flavors, or the largest sum |Re(x(i))|+|Im(x(i))| for complex flavors.

If n is not positive, 0 is returned.

If more than one vector element is found with the same largest absolute value, the index of the first one encountered is returned.

Input Parameters

n

INTEGER. Specifies the number of elements in vector x.

x

REAL for isamax

DOUBLE PRECISION for idamax

COMPLEX for icamax

DOUBLE COMPLEX for izamax

Array, DIMENSION at least (1+(n-1)*abs(incx)).

incx

INTEGER. Specifies the increment for the elements of x.

Output Parameters

index

INTEGER. Contains the position of vector element x that has the largest absolute value.

Fortran 95 Interface Notes

Functions and routines in Fortran 95 interface have fewer arguments in the calling sequence than their FORTRAN 77 counterparts. For general conventions applied to skip redundant or reconstructible arguments, see Fortran 95 Interface Conventions.

Specific details for the function iamax interface are the following:

x

Holds the vector with the number of elements n.