How to hide the menu programatically on a HP 48GX?

[Giuseppe Donnini]

Sure, use the PVIEW command with an empty list as its argument:

\<< { } PVIEW \>>

More generally speaking, PVIEW takes a coordinate pair as its argument and displays the picture screen in such a way that the upper left corner of the display shows the point corresponding to the specified coordinate pair. (Note that, if the given coordinate pair does not correspond to the top left corner of the picture, the latter must be large enough to fill the entire display window of 131 x 64 pixels; otherwise, you get a Bad Argument Value error.)

Coordinate pairs can be represented by either pixel coordinates or logical coordinates.

Pixel coordinates are expressed as lists of two binary integers: { #x #y }, where x is the column number, counting from left to right and beginning at column 0 at the left edge; and y is the row number, counting from up to down and beginning at row 0 at the top edge.

Logical coordinates, on the other hand, take into account the coordinate system imposed upon the picture screen by the plot parameters. They are expressed as complex numbers: (x,y), where x represents the abscissa and y the ordinate.

If PVIEW is given a logical coordinate pair or a non-empty pixel coordinate pair as its argument, it does not automatically freeze the display after showing it — which, by the way, is the mechanism that allows you to follow the progress of an ongoing plot, or, for that matter, to create any other kind of animated pictures. If you only want to show one “frame” (as is usually the case), you have to freeze the display yourself by means of the FREEZE command; otherwise, PVIEW will switch back to the text screen (typically showing the stack) before you can even take a look at your picture.

However, if PVIEW is given an empty list as its argument:

• the picture is centered in the display window,
• scrolling mode is activated (in case the picture is larger than the window),
• and the display is frozen until the [ON]-key is pressed.