nrm2 - Man Page

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

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.

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

Definition at line 89 of file dznrm2.f90.

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

Definition at line 89 of file scnrm2.f90.

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

Definition at line 88 of file snrm2.f90.