IDAMAX(3) BLAS routine of NEC Numeric Library Collection IDAMAX(3)
NAME
IDAMAX - BLAS level one, maximum index function
SYNOPSIS
INTEGER FUNCTION IDAMAX ( n, x, incx )
INTEGER n, incx
DOUBLE PRECISION x
DESCRIPTION
IDAMAX searches a double precision vector for the first occurrence of
the the maximum absolute value. The vector x has length n and increment
incx.
ARGUMENTS
n INTEGER. (input)
Number of elements to process in the vector to be searched. If
n <= 0, these routines return 0.
x DOUBLE PRECISION. (input)
Array of dimension (n-1) * |incx| + 1.
Array x contains the vector to be searched.
incx INTEGER. (input)
Increment between elements of x.
RETURN VALUES
IDAMAX INTEGER. (output)
Return the first index of the maximum absolute value of vector
x. The vector x has length n and increment incx.
NOTES
This routine is Level 1 Basic Linear Algebra Subprograms (Level 1
BLAS).
When working backward (incx < 0), each routine starts at the end of the
vector and moves backward, as follows:
x(1-incx * (n-1)), x(1-incx * (n-2)), ..., x(1)
The largest absolute value is:
ABS (x(1+(index-1) * incx)) when incx > 0
ABS (x(1+(n-index) * |incx|)) when incx < 0
BLAS routine IDAMAX(3)