HP 39g Master Manual page 223

.TRANSF.SHAPE
Assuming that you have
altered VIEWS menu then you can now test the aplet. Its operation should be
familiar to you if you have already examined its 'cousin' on page 194.
This program (left) uses the
CHOOSE command to offer a list of
options. Note the need to pre-load a
value into C. This value determines
which option is highlighted when the
menu appears. If a list has only
three options but the highlight is set
to some other value than those three
then it can crash the program.
Options 1 and 2 load preset
matrices while option 3 allows the
user to edit their own. Note the
check to ensure the matrix they
entered has a valid size. The
number of columns is then extracted
and used to reset the value of Tmax.
The new image matrix is also
recalculated.
The indenting used is not required
and is there simply to make the
program easier to read.
the .TRANSF.SV program to create the new
223
.TRANSF.MAT
This program puts up a message
instructing the user and then allows
them to edit the transformation
matrix in M1. The size of the matrix
is checked to ensure it is 2x2, with
the DO...UNTIL loop ensuring that
the user cannot exit without a valid
matrix entered.