F16JTF (BLAS_ZAMIN_VAL) (PDF version)
F16 Chapter Contents
F16 Chapter Introduction
NAG Library Manual

NAG Library Routine Document

F16JTF (BLAS_ZAMIN_VAL)

Note:  before using this routine, please read the Users' Note for your implementation to check the interpretation of bold italicised terms and other implementation-dependent details.

+− Contents

    1  Purpose
    2  Specification
    3  Description
    4  References
    5  Parameters
    6  Error Indicators and Warnings
    7  Accuracy
    8  Further Comments
+− 9  Example

1  Purpose

F16JTF (BLAS_ZAMIN_VAL) computes, with respect to absolute value, the smallest component of a complex vector, along with the index of that component.

2  Specification

SUBROUTINE F16JTF (N, X, INCX, K, R)
INTEGERN, INCX, K
double precisionR
complex*16X(1+(N-1)*ABS(INCX))
The routine may be called by its BLAS name blas_zamin_val.

3  Description

F16JTF (BLAS_ZAMIN_VAL) computes, with respect to absolute value, the smallest component, r, of an n-element complex vector x, and determines the smallest index, k, such that
r=Re⁡xk+Im⁡xk=minjRe⁡xj+Im⁡xj.

4  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

5  Parameters

1:     N – INTEGERInput
On entry: n, the number of elements in x.
2:     X(1+N-1×INCX) – complex*16 arrayInput
On entry: the vector x. Element xi is stored in Xi-1×INCX+1, for i=1,2,…,n.
3:     INCX – INTEGERInput
On entry: the increment in the subscripts of X between successive elements of x.
Constraint: INCX≠0.
4:     K – INTEGEROutput
On exit: k, the index, from the set 1,1+INCX,…,1+N-1×INCX , of the smallest component of x with respect to absolute value. If N≤0 on input then K is returned as 0.
5:     R – double precisionOutput
On exit: r, the smallest component of x with respect to absolute value. If N≤0 on input then R is returned as 0.0.

6  Error Indicators and Warnings

If INCX=0, an error message is printed and program execution is terminated.

7  Accuracy

Not applicable.

8  Further Comments

None.

9  Example

This example computes the smallest component with respect to absolute value and index of that component for the vector
x= -4+2.1i,3.7+4.5i,-6+1.2iT .

9.1  Program Text

Program Text (f16jtfe.f)

9.2  Program Data

Program Data (f16jtfe.d)

9.3  Program Results

Program Results (f16jtfe.r)

F16JTF (BLAS_ZAMIN_VAL) (PDF version)
F16 Chapter Contents
F16 Chapter Introduction
NAG Library Manual
© The Numerical Algorithms Group Ltd, Oxford, UK. 2009