# Gscaler

## Contents

### Purpose

GSCALER Applies group/block scaling to submatrices of a single matrix.

### Synopsis

- gys = gscaler(xin,numblocks,mxs,stdxs)
- xin = gscaler(gys,numblocks,mxs,stdxs,undo)

### Description

Inputs are a matrix (xin) (class "double"), the number of sub-matrices/ blocks (numblocks), an offset vector (mxs), and a scale vector (stdxs).

See GSCALE for descriptions of (mxs) and (stdxs).

Note that size(xin,2)/numblocks must be a whole number.

When numblocks = 1, all variables are scaled as a single block.

When numblocks = 0, each variable is handled on its own and gscaler is equivalent to the SCALE function.

If the optional input (undo) is included with a value of 1 (one), then the input is assumed to be (gys) and is unscaled and uncentered to give the original (xin) matrix.

In a standard call, the output is the scaled matrix (gys). When undo is provided, the output is the unscaled original matrix (xin).

### Examples

Scale a matrix a that has two blocks augmented together using GSCALE:

>> a = [[1 2 3; 4 5 6; 7 8 9] [11 12 13; 14 15 16; 17 18 19]]; >> [gxs,mxs,stdxs] = gscale(a,2); >> gxs gxs = -0.5774 -0.5774 -0.5774 -0.5774 -0.5774 -0.5774 0 0 0 0 0 0 0.5774 0.5774 0.5774 0.5774 0.5774 0.5774 >> mxs mxs = 4 5 6 14 15 16 >> stdxs stdxs = 3 3 3 3 3 3

Now scale a new matrix b that has two blocks augmented together:

>> b = [[2 3 4; 4 5 6; 6 7 8] [10 11 12; 14 15 16; 18 19 20]] b = 2 3 4 10 11 12 4 5 6 14 15 16 6 7 8 18 19 20 >> gys = gscaler(b,2,mxs,stdxs) gys = -0.3849 -0.3849 -0.3849 -0.7698 -0.7698 -0.7698 0 0 0 0 0 0 0.3849 0.3849 0.3849 0.7698 0.7698 0.7698