# dlas2.f - Man Page

## Synopsis

### Functions/Subroutines

subroutine **dlas2** (F, G, H, SSMIN, SSMAX)**DLAS2** computes singular values of a 2-by-2 triangular matrix.

## Function/Subroutine Documentation

### subroutine dlas2 (double precision F, double precision G, double precision H, double precision SSMIN, double precision SSMAX)

**DLAS2** computes singular values of a 2-by-2 triangular matrix.

**Purpose:**

DLAS2 computes the singular values of the 2-by-2 matrix [ F G ] [ 0 H ]. On return, SSMIN is the smaller singular value and SSMAX is the larger singular value.

**Parameters:***F*F is DOUBLE PRECISION The (1,1) element of the 2-by-2 matrix.

*G*G is DOUBLE PRECISION The (1,2) element of the 2-by-2 matrix.

*H*H is DOUBLE PRECISION The (2,2) element of the 2-by-2 matrix.

*SSMIN*SSMIN is DOUBLE PRECISION The smaller singular value.

*SSMAX*SSMAX is DOUBLE PRECISION The larger singular value.

**Author:**Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**December 2016

**Further Details:**

Barring over/underflow, all output quantities are correct to within a few units in the last place (ulps), even in the absence of a guard digit in addition/subtraction. In IEEE arithmetic, the code works correctly if one matrix element is infinite. Overflow will not occur unless the largest singular value itself overflows, or is within a few ulps of overflow. (On machines with partial overflow, like the Cray, overflow may occur if the largest singular value is within a factor of 2 of overflow.) Underflow is harmless if underflow is gradual. Otherwise, results may correspond to a matrix modified by perturbations of size near the underflow threshold.

Definition at line 109 of file dlas2.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dlas2(3) is an alias of dlas2.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK