# larmm - Man Page

larmm: scale factor to avoid overflow, step in latrs

## Synopsis

### Functions

double precision function **dlarmm** (anorm, bnorm, cnorm)**DLARMM**

real function **slarmm** (anorm, bnorm, cnorm)**SLARMM**

## Detailed Description

## Function Documentation

### double precision function dlarmm (double precision anorm, double precision bnorm, double precision cnorm)

**DLARMM**

**Purpose:**

DLARMM returns a factor s in (0, 1] such that the linear updates (s * C) - A * (s * B) and (s * C) - (s * A) * B cannot overflow, where A, B, and C are matrices of conforming dimensions. This is an auxiliary routine so there is no argument checking.

**Parameters***ANORM*ANORM is DOUBLE PRECISION The infinity norm of A. ANORM >= 0. The number of rows of the matrix A. M >= 0.

*BNORM*BNORM is DOUBLE PRECISION The infinity norm of B. BNORM >= 0.

*CNORM*CNORM is DOUBLE PRECISION The infinity norm of C. CNORM >= 0.

References: C. C. Kjelgaard Mikkelsen and L. Karlsson, Blocked Algorithms for Robust Solution of Triangular Linear Systems. In: International Conference on Parallel Processing and Applied Mathematics, pages 68--78. Springer, 2017.

Definition at line **60** of file **dlarmm.f**.

### real function slarmm (real anorm, real bnorm, real cnorm)

**SLARMM**

**Purpose:**

SLARMM returns a factor s in (0, 1] such that the linear updates (s * C) - A * (s * B) and (s * C) - (s * A) * B cannot overflow, where A, B, and C are matrices of conforming dimensions. This is an auxiliary routine so there is no argument checking.

**Parameters***ANORM*ANORM is REAL The infinity norm of A. ANORM >= 0. The number of rows of the matrix A. M >= 0.

*BNORM*BNORM is REAL The infinity norm of B. BNORM >= 0.

*CNORM*CNORM is REAL The infinity norm of C. CNORM >= 0.

References: C. C. Kjelgaard Mikkelsen and L. Karlsson, Blocked Algorithms for Robust Solution of Triangular Linear Systems. In: International Conference on Parallel Processing and Applied Mathematics, pages 68--78. Springer, 2017.

Definition at line **60** of file **slarmm.f**.

## Author

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