.TH "SRC/slassq.f90" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
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.SH NAME
SRC/slassq.f90
.SH SYNOPSIS
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.PP
.SS "Functions/Subroutines"

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.ti -1c
.RI "subroutine \fBslassq\fP (n, x, incx, scale, sumsq)"
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.RI "\fBSLASSQ\fP updates a sum of squares represented in scaled form\&. "
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine slassq (integer n, real(wp), dimension(*) x, integer incx, real(wp) scale, real(wp) sumsq)"

.PP
\fBSLASSQ\fP updates a sum of squares represented in scaled form\&.  
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\fBPurpose:\fP
.RS 4

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.nf
!>
!> SLASSQ returns the values scale_out and sumsq_out such that
!>
!>    (scale_out**2)*sumsq_out = x( 1 )**2 +\&.\&.\&.+ x( n )**2 + (scale**2)*sumsq,
!>
!> where x( i ) = X( 1 + ( i - 1 )*INCX )\&. The value of sumsq is
!> assumed to be non-negative\&.
!>
!> scale and sumsq must be supplied in SCALE and SUMSQ and
!> scale_out and sumsq_out are overwritten on SCALE and SUMSQ respectively\&.
!>
!> 
.fi
.PP
 
.RE
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\fBParameters\fP
.RS 4
\fIN\fP 
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!>          N is INTEGER
!>          The number of elements to be used from the vector x\&.
!> 
.fi
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\fIX\fP 
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!>          X is REAL array, dimension (1+(N-1)*abs(INCX))
!>          The vector for which a scaled sum of squares is computed\&.
!>             x( i ) = X( 1 + ( i - 1 )*INCX ), 1 <= i <= n\&.
!> 
.fi
.PP
.br
\fIINCX\fP 
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!>          INCX is INTEGER
!>          The increment between successive values of the vector 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\&.
!> 
.fi
.PP
.br
\fISCALE\fP 
.PP
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!>          SCALE is REAL
!>          On entry, the value scale in the equation above\&.
!>          On exit, SCALE is overwritten by scale_out, the scaling factor
!>          for the sum of squares\&.
!> 
.fi
.PP
.br
\fISUMSQ\fP 
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!>          SUMSQ is REAL
!>          On entry, the value sumsq in the equation above\&.
!>          On exit, SUMSQ is overwritten by sumsq_out, the basic sum of
!>          squares from which scale_out has been factored out\&.
!> 
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Edward Anderson, Lockheed Martin 
.RE
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\fBContributors:\fP
.RS 4
Weslley Pereira, University of Colorado Denver, USA Nick Papior, Technical University of Denmark, DK 
.RE
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\fBFurther Details:\fP
.RS 4

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.nf
!>
!>  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
!>
!> 
.fi
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.RE
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Definition at line \fB123\fP of file \fBslassq\&.f90\fP\&.
.SH "Author"
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Generated automatically by Doxygen for LAPACK from the source code\&.