[4.14] Completely Clear Graph Screen; [4.15] Delete Statistics Plots From Programs - Texas Instruments TI-89 Tip List

developing a comprehensive regenerative feedback theory. He invented techniques for synthesizing
networks with desired characteristics, which has applications in telephone line equalization. He also
worked with R. B. Blackman and Claude Shannon to model messages and signals in probabilistic
terms, which was a new idea at the time.
Hendrik Bode is obviously not the other well-know Bode, the German astronomer Johann Elert Bode,
who lived from 1747 to 1826. J.E. Bode compiled an astronomical atlas for 51 consecutive years, and
also, unfortunately, his name is associated with a flawed theory to predict the location of planetary
orbits.

[4.14] Completely clear Graph screen

Some programs may require completely clearing the Graph screen of plots, functions, axes and so on.
This program does it:
graphClr()
Prgm
©Completely clear Graph screen
local ä
StoPic ä
XorPic ä
DelVar ä
EndPrgm
The method works by exclusive-ORing the current graph screen with itself, clearing all the pixels. This
method is much simpler than using the built-in commands to clear the functions, plots, axes and so on.
(Credit to Kevin Kofler)

[4.15] Delete statistics plots from programs

There is no TI Basic function or command which will delete a statistics plot (the 'plots' in the Y= editor),
which is unfortunate, because it is often useful in a program to create plots, then delete them when the
program finishes.
The work-around is to save the user's plot definitions with StoGDB before creating the plots, then
restore the definitions with RclGDB before the program terminates.
(Credit to Titmité Hassan)
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