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Dataplot Vol 2 Vol 1

CREATE MATRIX

Name:
    CREATE MATRIX (LET)
Type:
    Let Subcommand
Purpose:
    Create a matrix from a list of variables.
Description:
    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.

Syntax:
    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).
Examples:
    LET C = CREATE MATRIX X0 X1 X2 X3 X4
Note:
    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.
Note:
    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.

Note:
    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.
Default:
    None
Synonyms:
    None
Related Commands:
    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.
Applications:
    Matrix Operations
Implementation Date:
    2002/7
Program:
    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 
        

Date created: 8/6/2002
Last updated: 4/4/2003
Please email comments on this WWW page to alan.heckert@nist.gov.