Name

isamin, idamin, icamin, izamin − Index of the element of a vector with minimum absolute value

FORMAT

I{S,D,C,Z}AMIN (n, x, incx)

Function Value

imininteger∗4

The index of the first element of the vector x such that (X(1+(imin-1)∗|incx|)) is the smallest in absolute value of all elements of the vector.  If n<=0, imin returns the value 0. 

Arguments

ninteger∗4
On entry, the number of elements in the vector x.
On exit, n is unchanged. 

xreal∗4 | real∗8 |  complex∗8 |  complex∗16
On entry, a one-dimensional array X of length at least (1+(n-1)∗|incx|), containing the elements of the vector x.
On exit, x is unchanged. 

incxinteger∗4
On entry, the increment for the array X.
If incx > 0, vector x is stored forward in the array, so that x(i) is stored in location X(1+(i-1)∗incx). 
If incx < 0, vector x is stored backward in the array, so that x(i) is stored in location X(1+(n-i)∗|incx|). 
If incx = 0, only the first element is accessed. 
On exit, incx is unchanged. 

Description

These subprograms compute the index of the element of a  vector having the minimum absolute value. They determine the first integer i of the vector x such that: |x(i)| = MAX{|x(j)|, j = 1,2, ...,n}
For complex vectors, each element x(j) is a complex number. In this subprogram, the absolute value of a complex number is defined as the absolute value of the real part of the complex number plus the absolute value of the imaginary part of the complex number: |x(j)| = |a(j)| + |b(j)| = |(real)| + |(imaginary)|

If incx = 0, the computation is a time-consuming way of setting imin = 1. 

Example

INTEGER∗4 N, INCX, IMIN
REAL∗4 X(40)
INCX = 2
N = 20
IMIN = ISAMIN(N,X,INCX)

This FORTRAN example shows how to compute the index of the vector element with minimum absolute value.