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39.2 Functions and Variables for alt-display

Function: alt_display_output_type (form)

Determine the type of output to be printed. Form must be a lisp form suitable for printing via Maxima’s built-in displa function. At present, this function returns one of three values: text, label or unknown.

An example where alt_display_output_type is used. In my_display, a text form is printed between a pair of tags TEXT;>> and <<TEXT; while a label form is printed between a pair tags OUT;>> and <<OUT; in addition to the usual output label.

The function set_prompt also ensures that input labels are printed between matching PROMPT;>> and <<PROMPT; tags.

Thanks to Eric Stemmler. 

(%i1) (load("mactex-utilities"), load("alt-display.mac")) $

(%i2) define_alt_display(my_display(form),
block([type,txttmplt,labtmplt], 
txttmplt:"~%TEXT;>>~%~a~%<<TEXT;~%",
labtmplt:"~%OUT;>>~%(~a) ~a~a~a~%<<OUT;~%",
type:alt_display_output_type(form),
if type='text then 
   printf(true,txttmplt,first(form))
else if type='label then 
     printf(true,labtmplt,first(form),"$$",tex1(second(form)),"$$")
else 
     block([alt_display1d:false, alt_display2d:false], displa(form)))) $

(%i3) (set_prompt('prefix, "PROMPT;>>",'suffix, "<<PROMPT;"), 
      set_alt_display(1,my_display)) $

PROMPT;>>(%i4) <<PROMPT;integrate(x^n,x);
PROMPT;>>
TEXT;>>
Is n equal to -1?
<<TEXT;
<<PROMPT;
n;

OUT;>>
(%o4) $$\frac{x^{n+1}}{n+1}$$
<<OUT;
PROMPT;>>(%i5) <<PROMPT;
Categories: Package alt-display ·
Function: define_alt_display (function(input), expr)

This function is similar to define: it evaluates its arguments and expands into a function definition. The function is a function of a single input input. For convenience, a substitution is applied to expr after evaluation, to provide easy access to Lisp variable names.

Set a time-stamp on each prompt: 

(%i1) load("alt-display.mac")$

(%i2) display2d: false$

(%i3) define_alt_display(time_stamp(x),
                block([alt_display1d:false,alt_display2d:false],
                      prompt_prefix:printf(false,"~a~%",timedate()),
                      displa(x)));

(%o3) time_stamp(x):=block(
                 [\*alt\-display1d\*:false,
                  \*alt\-display2d\*:false],
                 \*prompt\-prefix\*
                  :printf(false,"~a~%",timedate()),displa(x))
(%i4) set_alt_display(1,time_stamp);

(%o4) done
2017-11-27 16:15:58-06:00
(%i5)

The input line %i3 defines time_stamp using define_alt_display. The output line %o3 shows that the Maxima variable names alt_display1d, alt_display2d and prompt_prefix have been replaced by their Lisp translations, as has displa been replaced by ?displa (the display function).

The display variables alt_display1d and alt_display2d are both bound to false in the body of time_stamp to prevent an infinite recursion in displa.

Categories: Package alt-display ·
Function: info_display (form)

This is an alias for the default 1-d display function. It may be used as an alternative 1-d or 2-d display function. 

(%i1) load("alt-display.mac")$

(%i2) set_alt_display(2,info_display);

(%o2) done
(%i3) x/y;

(%o3) x/y
Categories: Package alt-display ·
Function: mathml_display (form)

Produces MathML output. 

(%i1) load("alt-display.mac")$

(%i2) set_alt_display(2,mathml_display);
<math xmlns="http://www.w3.org/1998/Math/MathML"> <mi>mlabel</mi> 
 <mfenced separators=""><msub><mi>%o</mi> <mn>2</mn></msub> 
 <mo>,</mo><mi>done</mi> </mfenced> </math>
Categories: Package alt-display ·
Function: tex_display (form)

Produces TeX output. 

(%i2) set_alt_display(2,tex_display);
\mbox{\tt\red({\it \%o_2}) \black}$$\mathbf{done}$$
(%i3) x/(x^2+y^2);
\mbox{\tt\red({\it \%o_3}) \black}$${{x}\over{y^2+x^2}}$$
Categories: Package alt-display ·
Function: multi_display_for_texinfo (form)

Produces Texinfo output using all three display functions. 

(%i2) set_alt_display(2,multi_display_for_texinfo)$

(%i3) x/(x^2+y^2);

@iftex
@tex
\mbox{\tt\red({\it \%o_3}) \black}$${{x}\over{y^2+x^2}}$$
@end tex
@end iftex
@ifhtml
@html

   <math xmlns="http://www.w3.org/1998/Math/MathML"> <mi>mlabel</mi> 
   <mfenced separators=""><msub><mi>%o</mi> <mn>3</mn></msub> 
   <mo>,</mo><mfrac><mrow><mi>x</mi> </mrow> <mrow><msup><mrow>
   <mi>y</mi> </mrow> <mn>2</mn> </msup> <mo>+</mo> <msup><mrow>
   <mi>x</mi> </mrow> <mn>2</mn> </msup> </mrow></mfrac> </mfenced> </math>
@end html
@end ifhtml
@ifinfo
@example
(%o3) x/(y^2+x^2)
@end example
@end ifinfo
Categories: Package alt-display ·
Functions: reset_displays ()

Resets the prompt prefix and suffix to the empty string, and sets both 1-d and 2-d display functions to the default.

Categories: Package alt-display ·
Function: set_alt_display (num, display-function)

The input num is the display to set; it may be either 1 or 2. The second input display-function is the display function to use. The display function may be either a Maxima function or a lambda expression.

Here is an example where the display function is a lambda expression; it just displays the result as TeX. 

(%i1) load("alt-display.mac")$

(%i2) set_alt_display(2, lambda([form], tex(?caddr(form))))$

(%i3) integrate(exp(-t^2),t,0,inf);
$${{\sqrt{\pi}}\over{2}}$$

A user-defined display function should take care that it prints its output. A display function that returns a string will appear to display nothing, nor cause any errors.

Categories: Package alt-display ·
Function: set_prompt (fix, expr)

Set the prompt prefix or suffix to expr. The input fix must evaluate to one of prefix, suffix, general, prolog or epilog. The input expr must evaluate to either a string or false; if false, the fix is reset to the default value. 

(%i1) load("alt-display.mac")$
(%i2) set_prompt('prefix,printf(false,"It is now: ~a~%",timedate()))$

It is now: 2014-01-07 15:23:23-05:00
(%i3)

The following example shows the effect of each option, except prolog. Note that the epilog prompt is printed as Maxima closes down. The general is printed between the end of input and the output, unless the input line ends in $.

Here is an example to show where the prompt strings are placed. 

(%i1) load("alt-display.mac")$

(%i2) set_prompt(prefix, "<<prefix>> ", suffix, "<<suffix>> ",
                 general, printf(false,"<<general>>~%"),
                 epilog, printf(false,"<<epilog>>~%"));

(%o2)                                done
<<prefix>> (%i3) <<suffix>> x/y;
<<general>>
                                       x
(%o3)                                  -
                                       y
<<prefix>> (%i4) <<suffix>> quit();
<<general>>
<<epilog>>

Here is an example that shows how to colorize the input and output when Maxima is running in a terminal or terminal emulator like Emacs8.

./figures/color_terminal

Each prompt string starts with the ASCII escape character (27) followed by an open square bracket (91); each string ends with a lower-case m (109). The webpages https://misc.flogisoft.com/bash/tip_colors_and_formatting and https://www.tldp.org/HOWTO/Bash-Prompt-HOWTO/x329.html provide information on how to use control strings to set the terminal colors.

Categories: Package alt-display ·

Footnotes

(8)

Readers using the info reader in Emacs will see the actual prompt strings; other readers will see the colorized output

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