MATRIX TRUNCATION

MATRIX TRUNCATION (LET)

Let Subcommand

Set all elements in a matrix less than (or greater than) a specified value to that value.

The primary motivation for this command is to subtract a background value from a matrix. This can be accomplished by using the MATRIX SUBTRACT command to subtract the background value and then using the MATRIX TRUNCATION command to set all negative values to zero.

LET <Z> = MATRIX TRUNCATION <M> <VALUE>
where <M> is a matrix;
            <VALUE> is a parameter or a number that specifies the truncation value;
and     <Z> is the matrix that is returned after the truncation is applied.


This syntax is used to perform lower truncation (that is, any values less than <VALUE> are set equal to <VALUE>. The <Z> matrix can be the same as the <M> matrix.

LET <Z> = MATRIX UPPER TRUNCATION <M> <VALUE>
where <M> is a matrix;
            <VALUE> is a parameter or a number that specifies the truncation value;
and     <Z> is the matrix that is returned after the truncation is applied.


This syntax is used to perform upper truncation (that is, any values greater than <VALUE> are set equal to <VALUE>. The <Z> matrix can be the same as the <M> matrix.

LET VALUE = 8
LET M = MATRIX TRUNCATION M VALUE

None

MATRIX LOWER TRUNCATION is a synonym for MATRIX TRUNCATION

MATRIX SUBTRACTION	= Perform matrix subtraction.
MATRIX ADDITION	= Perform matrix addition.
MATRIX MULTIPLICATION	= Perform matrix multiplication.

Matrix Arithmetic

2006/3

 
READ MATRIX M
 1  2  3
 4  5  6
 7  8  9
10 11 12
END OF DATA
.
LET ZERO = 0
LET AVAL = 4
LET M = MATRIX SUBTRACTION M AVAL
LET M = MATRIX TRUNCATION M ZERO
.
SET WRITE DECIMALS 0
PRINT M
    

The resulting M matrix is:

 
         MATRIX M       --            4 ROWS
                        --            3 COLUMNS

 VARIABLES--M1             M2             M3

          0              0              0
          0              1              2
          3              4              5
          6              7              8