CREATE MATRIX

CREATE MATRIX (LET)

Let Subcommand

Create a matrix from a list of variables.

A number of commands in Dataplot operate on a matrix. The CREATE MATRIX command can be a convenient way to create a matrix from a list of variables.

This command has a similar function to the MATRIX DEFINITION command. The distinction is that the MATRIX DEFINITION command creates a matrix from variables that are stored contiguously in the Dataplot variable space (variables are stored in the order that they are created). The CREATE MATRIX command does not impose this restriction.

LET <mat1> = CREATE MATRIX <var1> ... <vark>
                            <SUBSET/EXCEPT/FOR qualification>
where <var1> ... <vark> is a list of 1 to 30 previously defined variables;
              <mat1> is a matrix where the resulting matrix is saved; and where the <SUBSET/EXCEPT/FOR qualification> is optional (and rarely used in this context).

LET C = CREATE MATRIX X0 X1 X2 X3 X4

The 2023/05 version of Dataplot update the CREATE MATRIX command to support the "TO" syntax. That is, you can now enter commands such as
LET M = CREATE MATRIX X1 TO X50
LET M = CREATE MATRIX X3 X8 TO X24 X28

The columns of a matrix are accessible as variables by appending an index to the matrix name. For example, the 4x4 matrix C has columns C1, C2, C3, and C4. These columns can be operated on like any other DATAPLOT variable.

The original variables are not deleted. This command creates new copies of the variables.

To create a matrix from a list of variables without creating a duplicate copy of the variables, do something like the following:

WRITE TEMP.OUT X0 X1 X2 X3 X4
DELETE X0 X1 X2 X3 X4
READ MATRIX TEMP.OUT X


Be aware that the variable names are now X1, X2, X3, X4, and X5.

The maximum size matrix that DATAPLOT can handle is set when DATAPLOT is built on a particular site. Enter the command HELP MATRIX DIMENSION for details on the maximum size matrix that can be accomodated.

None

None

MATRIX DEFINITION	= Create a matrix from contiguous variables.
CATCHER MATRIX	= Compute the catcher matrix.
VARIANCE INFLATION FACTORS	= Compute variance inflation factors.
CONDITION INDICES	= Compute condition indices.
XTXINV MATRIX	= Compute the (X'X)**(-1) matrix.

Matrix Operations

2002/07
2023/05: Added support for "TO" syntax

DIMENSION 100 COLUMNS 
SKIP 25  
READ HALD647.DAT Y X1 X2 X3 X4  
LET N = SIZE X1  
LET X0 = SEQUENCE 1 1 N  
LET Z = CREATE MATRIX X0 X1 X2 X3 X4  
.  
LET C = CONDITION INDICES Z