# Matrix

``` BBS: Inland Empire Archive
Date: 04-30-92 (21:21)             Number: 194
From: PAUL LEONARD                 Refer#: 147
To: MARGARET ROMAO                Recvd: NO
Subj: Matrix                         Conf: (2) Quik_Bas```
```On or about <Apr 29 11:26>, Margaret Romao (1:3603/150) scribbled:

MR> What did the MAT function do?

The following is from the Basic-Plus2 help listings...

BP2

MAT_INPUT
MAT INPUT array(s)
50 MAT INPUT A
The MAT INPUT statement assigns data you input to the elements
of a specified array.  Elements are stored in row order as they
are typed.
MAT INPUT #
MAT INPUT #num-exp%, array name
100 MAT INPUT #2%, ARN
The MAT INPUT # statement reads values from a terminal format
file and assigns them to a specified array.  The elements are
stored in the destination array in row order.

MAT_LINPUT
MAT LINPUT string array name
300 MAT LINPUT VECTOR.NAME\$
The MAT LINPUT statement assigns data you input to elements of
a string array.
MAT LINPUT #
MAT LINPUT #num-exp% string array name
90 MAT LINPUT #1%,A\$
The MAT LINPUT statement reads string data from a terminal
format file and assigns it to elements of a string array.
MAT LINPUT # does not include the string's line terminator
as part of the array element.

MAT_PRINT
MAT PRINT array(s)
120 MAT PRINT A;
The MAT PRINT statement prints all elements of a specified
array.
MAT PRINT #
MAT PRINT #num-exp%, array name
60 MAT PRINT #5%, TESTAR
MAT PRINT # prints the contents of an array to a terminal
format file.

elements of a 1- or 2-dimensional array.

MATRIX_ASSIGNMENT
MAT array name = array name
15 MAT A = B
In matrix assignment, the MAT statement sets each entry of
Array A equal to the corresponding entry of Array B.  A is
redimensioned to the size of B.

IDN
Sets up an identity matrix:  all elements are zero
except for those on the (I,I) diagonal, which are set
to one.

INV
Generates a matrix that is the inverse of another.  For
example, MAT N = INV(M) makes Matrix N the inverse of
Matrix M.  Matrix M must be a square matrix.

...All of these functions are just specialized array
functions and can be implemented with FOR...NEXT loops.
For example, the IDN(mat) can be coded with...

DIM mat%(10,10)

FOR i%=1 to 10
FOR j%=1 to 10
IF i%=j% then mat%(i%,j%)=1 else mat%(i%,j%)=0
NEXT j%
NEXT i%

ptl

--- msged 2.07
* Origin: PTL Pointwork (1:105/48.111)
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