---
name: "dlassq"
section: "3lapack"
platform: "linux"
package: "liblapack-doc"
version: "3.2.1-8"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/dlassq/3lapack"
---

# dlassq(3lapack)

returns the values scl and smsq such that ( scl\*\*2 )\*smsq = x( 1 )\*\*2 +...+ x( n )\*\*2 + ( scale\*\*2 )\*sumsq,

## NAME

DLASSQ - returns the values scl and smsq such that   ( scl\*\*2 )\*smsq = x( 1 )\*\*2 +...+ x( n )\*\*2 + ( scale\*\*2 )\*sumsq,

## SYNOPSIS

- SUBROUTINE DLASSQ(

  N, X, INCX, SCALE, SUMSQ )

- INTEGER

  INCX, N

- DOUBLE

  PRECISION SCALE, SUMSQ

- DOUBLE

  PRECISION X( \* )

## PURPOSE

DLASSQ  returns the values  scl  and  smsq  such that where  x( i ) = X( 1 + ( i - 1 )\*INCX ). The value of  sumsq  is assumed to be non-negative and  scl  returns the value\
\
    scl = max( scale, abs( x( i ) ) ).\
 scale and sumsq must be supplied in SCALE and SUMSQ and\
 scl and smsq are overwritten on SCALE and SUMSQ respectively. The routine makes only one pass through the vector x.\

## ARGUMENTS

- N (input) INTEGER

  The number of elements to be used from the vector X.

- X (input) DOUBLE PRECISION array, dimension (N)

  The vector for which a scaled sum of squares is computed. x( i )  = X( 1 + ( i - 1 )\*INCX ), 1 \<= i \<= n.

- INCX (input) INTEGER

  The increment between successive values of the vector X. INCX \> 0.

- SCALE (input/output) DOUBLE PRECISION

  On entry, the value  scale  in the equation above. On exit, SCALE is overwritten with  scl , the scaling factor for the sum of squares.

- SUMSQ (input/output) DOUBLE PRECISION

  On entry, the value  sumsq  in the equation above. On exit, SUMSQ is overwritten with  smsq , the basic sum of squares from which  scl  has been factored out.