Man page - nrm2(3)

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Manual

nrm2

NAME
SYNOPSIS
Functions
Detailed Description
Function Documentation
real(wp) function dnrm2 (integer n, real(wp), dimension(*) x, integer incx)
real(wp) function dznrm2 (integer n, complex(wp), dimension(*) x, integerincx)
real(wp) function scnrm2 (integer n, complex(wp), dimension(*) x, integerincx)
real(wp) function snrm2 (integer n, real(wp), dimension(*) x, integer incx)
Author

NAME

nrm2 - nrm2: || x ||_2

SYNOPSIS

Functions

real(wp) function dnrm2 (n, x, incx)
DNRM2
real(wp) function dznrm2 (n, x, incx)
DZNRM2
real(wp) function scnrm2 (n, x, incx)
SCNRM2
real(wp) function snrm2 (n, x, incx)
SNRM2

Detailed Description

Function 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

real(wp) function dznrm2 (integer n, complex(wp), dimension(*) x, integerincx)

DZNRM2

Purpose:

DZNRM2 returns the euclidean norm of a vector via the function
name, so that

DZNRM2 := sqrt( x**H*x )

Parameters

N

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

X

X is COMPLEX*16 array, dimension (N)
complex vector with N elements

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

real(wp) function scnrm2 (integer n, complex(wp), dimension(*) x, integerincx)

SCNRM2

Purpose:

SCNRM2 returns the euclidean norm of a vector via the function
name, so that

SCNRM2 := sqrt( x**H*x )

Parameters

N

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

X

X is COMPLEX array, dimension (N)
complex vector with N elements

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

real(wp) function snrm2 (integer n, real(wp), dimension(*) x, integer incx)

SNRM2

Purpose:

SNRM2 returns the euclidean norm of a vector via the function
name, so that

SNRM2 := sqrt( x’*x ).

Parameters

N

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

X

X is REAL 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

Author

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