# slassq.f man page

slassq.f —

## Synopsis

### Functions/Subroutines

subroutineslassq(N, X, INCX, SCALE, SUMSQ)SLASSQupdates a sum of squares represented in scaled form.

## Function/Subroutine Documentation

### subroutine slassq (integerN, real, dimension( * )X, integerINCX, realSCALE, realSUMSQ)

**SLASSQ** updates a sum of squares represented in scaled form.

**Purpose:**

```
SLASSQ returns the values scl and smsq such that
( scl**2 )*smsq = 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 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.
```

**Parameters:**

*N*

```
N is INTEGER
The number of elements to be used from the vector X.
```

*X*

```
X is REAL 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*

```
INCX is INTEGER
The increment between successive values of the vector X.
INCX > 0.
```

*SCALE*

```
SCALE is REAL
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*

```
SUMSQ is REAL
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.
```

**Author:**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**

September 2012

Definition at line 104 of file slassq.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

slassq(3) is an alias of slassq.f(3).