MATRIX SCALE
Name:
Type:
Purpose:
Description:
For some computations, such as computing a distance matrix,
it may be desirable to scale the matrix first. The scaling
may be performed over either rows or columns.
Dataplot supports the following types of scaling.
 MEAN  subtract the column mean from each column of
the matrix (or subtract the row mean from each row).
 SD  divide each column by the column standard
deviation (or divide each row by the row standard
deviation).
 ZSCORE  subtract the column mean and then divide by
the column standard deviation for each column (or
subtract the row mean and divide by the row standard
deviation for each row).
 RANGE  divide each column by the column range
(or divide each row by the row range).
The type of scaling is specified by entering the command
SET MATRIX SCALE <NONE/MEAN/SD/ZSCORE/RANGE>
Specifying NONE applies no scaling.
Syntax 1:
Syntax 2:
LET <mat2> = MATRIX COLUMN SCALE <mat1>
where <mat1> is a matrix for which the matrix scaling
is to be computed;
and where <mat2> is a matrix where the resulting
scaled matrix is saved.
This syntax scales relative to columns. The scaled matrix
can be the same as the original data matrix.
Examples:
Note:
Matrices are created with either the READ MATRIX command or the
MATRIX DEFINITION command. Enter HELP MATRIX DEFINITION and HELP
READ MATRIX for details.
Default:
Synonyms:
Related Commands:
READ MATRIX

= Read a matrix.

MATRIX COLUMN DIMENSION

= Dimension maximum number of
columns for Dataplot matrices.

MATRIX DISTANCE

= Compute a distance matrix.

Reference:
"Applied Multivariate Statistical Analysis", Third Edition,
Johnson and Wichern, PrenticeHall, 1992.
Applications:
Implementation Date:
Program:
DIMENSION 200 COLUMNS
SKIP 25
READ IRIS.DAT SEPLENG SEPWIDTH PETLENG PETWIDTH TAG
SKIP 0
LET NTOT = SIZE SEPLENG
LET X = MATRIX DEFINITION SEPLENG NTOT 4
SET MATRIX SCALE ZSCORE
LET X = MATRIX COLUMN SCALING X
Date created: 6/5/2001
Last updated: 4/4/2003
Please email comments on this WWW page to
alan.heckert@nist.gov.
