Minimum of magnitudes

 

SAMIN/DAMIN/IAMIN/SCAMIN/DZAMIN

Input

n

Number of elements of vector x to be used. If n ≤ 0, the

 

 

subprograms do not reference x.

 

x

Array of length lenx = (n−1)⋅incx+1 containing the

 

 

n-vector x.

 

incx

Increment for array x. x is stored forward in array x

 

 

with increment incx; that is, xi is stored in

 

 

x((i−1)⋅incx+1).

 

 

Use incx = 1 if the vector x is stored contiguously in

 

 

array x; that is, if xi is stored in x(i). Refer to “BLAS

 

 

Indexing Conventions” in the introduction to this

 

 

chapter.

Output

s

If n ≤ 0, then s = ∞, the largest representable machine

 

 

number. Otherwise, s is the minimum of the

 

 

magnitudes of the elements of x.

Fortran Equivalent

REAL*4 FUNCTION SAMIN (N,X,INCX) REAL*4 X(*)

SAMIN = ∞

INCXA = ABS ( INCX ) IX = 1

DO 10 I = 1, N

SAMIN = MIN ( SAMIN , ABS ( X(IX) ) )

IX = IX + INCXA

10CONTINUE RETURN END

Example Compute the minimum of the magnitudes of the elements of a REAL*8 vector x, where x is a vector 10 elements long stored in a one-dimensional array X of dimension 20.

INTEGER*4

N,INCX

REAL*8

S,DAMIN,X(20)

N =

10

 

INCX = 1

 

S =

DAMIN (N,X,INCX)

Chapter 2 Basic Vector Operations 61