# dnrm2.f90 - Man Page

BLAS/SRC/dnrm2.f90

## Synopsis

### Functions/Subroutines

real(wp) function dnrm2 (n, x, incx)
DNRM2

## Function/Subroutine Documentation

### real(wp) function dnrm2 (integer n, real(wp), dimension(*) x, integer incx)

DNRM2

Purpose:

``` DNRM2 returns the euclidean norm of a vector via the function
name, so that

DNRM2 := sqrt( x'*x )```
Parameters

N

```          N is INTEGER
number of elements in input vector(s)```

X

`          X is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) )`

INCX

```          INCX is INTEGER, storage spacing between elements of X
If INCX > 0, X(1+(i-1)*INCX) = x(i) for 1 <= i <= n
If INCX < 0, X(1-(n-i)*INCX) = x(i) for 1 <= i <= n
If INCX = 0, x isn't a vector so there is no need to call
this subroutine.  If you call it anyway, it will count x(1)
in the vector norm N times.```
Author

Edward Anderson, Lockheed Martin

Date

August 2016

Contributors:

Weslley Pereira, University of Colorado Denver, USA

Further Details:

```  Anderson E. (2017)
Algorithm 978: Safe Scaling in the Level 1 BLAS
ACM Trans Math Softw 44:1--28
https://doi.org/10.1145/3061665

Blue, James L. (1978)
A Portable Fortran Program to Find the Euclidean Norm of a Vector
ACM Trans Math Softw 4:15--23
https://doi.org/10.1145/355769.355771```

Definition at line 88 of file dnrm2.f90.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dnrm2(3) is an alias of dnrm2.f90(3).

Tue Nov 28 2023 12:08:41 Version 3.12.0 LAPACK