| nrm2(3) | LAPACK | nrm2(3) |
nrm2 - nrm2: || x ||_2
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 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
Date
Contributors:
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
DZNRM2
Purpose:
DZNRM2 returns the euclidean norm of a vector via the function
name, so that
DZNRM2 := sqrt( x**H*x )
Parameters
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
Date
Contributors:
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
SCNRM2
Purpose:
SCNRM2 returns the euclidean norm of a vector via the function
name, so that
SCNRM2 := sqrt( x**H*x )
Parameters
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
Date
Contributors:
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
SNRM2
Purpose:
SNRM2 returns the euclidean norm of a vector via the function
name, so that
SNRM2 := sqrt( x'*x ).
Parameters
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
Date
Contributors:
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
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