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NAG Toolbox: nag_blast_damin_val (f16jr)

Purpose

nag_blast_damin_val (f16jr) computes, with respect to absolute value, the smallest component of a real vector, along with the index of that component.

Syntax

[k, r] = f16jr(n, x, incx)
[k, r] = nag_blast_damin_val(n, x, incx)

Description

nag_blast_damin_val (f16jr) computes, with respect to absolute value, the smallest component, rr, of an nn-element real vector xx, and determines the smallest index, kk, such that
r = |xk| = min |xj|.
j
r=|xk|=minj|xj|.

References

Basic Linear Algebra Subprograms Technical (BLAST) Forum (2001) Basic Linear Algebra Subprograms Technical (BLAST) Forum Standard University of Tennessee, Knoxville, Tennessee http://www.netlib.org/blas/blast-forum/blas-report.pdf

Parameters

Compulsory Input Parameters

1:     n – int64int32nag_int scalar
nn, the number of elements in xx.
2:     x(1 + (n1) × |incx|1+(n-1)×|incx|) – double array
The vector xx. Element xixi is stored in x((i1) × |incx| + 1)x(i-1)×|incx|+1, for i = 1,2,,ni=1,2,,n.
3:     incx – int64int32nag_int scalar
The increment in the subscripts of x between successive elements of xx.
Constraint: incx0incx0.

Optional Input Parameters

None.

Input Parameters Omitted from the MATLAB Interface

None.

Output Parameters

1:     k – int64int32nag_int scalar
kk, the index, from the set {1,1 + |incx|,,1 + (n1) × |incx|} {1,1+|incx|,,1+(n-1)×|incx|} , of the smallest component of xx with respect to absolute value. If n0n0 on input then k is returned as 00.
2:     r – double scalar
rr, the smallest component of xx with respect to absolute value. If n0n0 on input then r is returned as 0.00.0.

Error Indicators and Warnings

Accuracy

The BLAS standard requires accurate implementations which avoid unnecessary over/underflow (see Section 2.7 of Basic Linear Algebra Subprograms Technical (BLAST) Forum (2001)).

Further Comments

None.

Example

function nag_blast_damin_val_example
n = int64(5);
x = [1;
     10;
     11;
     -2;
     9];
incx = int64(1);
[k, r] = nag_blast_damin_val(n, x, incx)
 

k =

                    1


r =

     1


function f16jr_example
n = int64(5);
x = [1;
     10;
     11;
     -2;
     9];
incx = int64(1);
[k, r] = f16jr(n, x, incx)
 

k =

                    1


r =

     1



PDF version (NAG web site, 64-bit version, 64-bit version)
Chapter Contents
Chapter Introduction
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