HP 39g Master Manual page 195

The result is a triangle with corners at (1,1),
(2,1) and (1,3), along with its image after
reflection in the x axis.
We can now
another matrix. For example:
To see the effect of this new matrix, simply
return to the HOME view,
calculation and press ENTER. The new image
will be stored into matrix M3. If you now return
to the PLOT view the image will not appear to
have changed as the aplet does not realize the
matrix has changed but pressing PLOT again
will force a re-draw of the new image.
The power of this aplet as an investigative tool is that you can now continue
to matrix M1, repeat the HOME calculation, and re-plot to see
immediately the change in the image.
The degree of guidance which should be given to a class will obviously
depend on their level of ability. You might choose simply to suggest that they
confine their investigations initially to placing numbers only on the diagonals.
It is a good idea to challenge them to record their matrices on the board as
they discovered them. A highly able class will find nearly all relevant matrices
within 20 to 30 minutes.
So... how does this aplet work?
The formulas in the SYMB view form the key to
the process by allowing the calculator to fetch
values from the matrices, with the values
fetched being determined by the settings in the
PLOT SETUP view. For example, as T runs
from 1 to 4 in steps of 1 the (X1,Y1) values
plotted become (
M2(1,1)
( ) and (
,
M2(1,3) M2(2,3) M2(1,4)
substitute the actual values from matrix M2 then these points become (1,1),
(2,1), (3,1) and (1,1), which give the shape when plotted. The repetition of the
first point is to ensure that the line forming the triangle is closed by
connecting back to its starting point. Obviously X2 and Y2 perform the same
function with matrix M3.
matrix M1 so that it contains
−

1 0

 0 1

the previous
), (
, ,
M2(2,1) M2(1,2) M2(2,2)
). If we now
,
M2(2,4)




),
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