39. alt-display
39.1 Introduction to alt-display
The alt-display package provides a means to change the way that
Maxima displays its output. The *alt-display1d* and
*alt-display2d* Lisp hooks were introduced to Maxima in 2002, but
were not easily accessible from the Maxima REPL until the introduction
of this package.
The package provides a general purpose function to define alternative
display functions, and a separate function to set the display
function. The package also provides customized display functions to
produce output in TeX, Texinfo, XML and all three output formats
within Texinfo.
Here is a sample session:
(%i1) load("alt-display.mac")$
(%i2) set_alt_display(2,tex_display)$
(%i3) x/(x^2+y^2) = 1;
\mbox{\tt\red({\it \%o_3}) \black}$${{x}\over{y^2+x^2}}=1$$
(%i4) set_alt_display(2,mathml_display)$
(%i5) x/(x^2+y^2) = 1;
<math xmlns="http://www.w3.org/1998/Math/MathML"> <mi>mlabel</mi>
<mfenced separators=""><msub><mi>%o</mi> <mn>5</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> <mo>=</mo>
<mn>1</mn> </mfenced> </math>
(%i6) set_alt_display(2,multi_display_for_texinfo)$
(%i7) x/(x^2+y^2) = 1;
@iftex
@tex
\mbox{\tt\red({\it \%o_7}) \black}$${{x}\over{y^2+x^2}}=1$$
@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>7</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> <mo>=</mo>
<mn>1</mn> </mfenced> </math>
@end html
@end ifhtml
@ifinfo
@example
(%o7) x/(y^2+x^2) = 1
@end example
@end ifinfo
If the alternative display function causes an error, the error is
trapped and the display function is reset to the default display. In the
following example, the error function is set to display the
output. This throws an error, which is handled by resetting the
2d-display to the default.
(%i8) set_alt_display(2,?error)$
(%i9) x;
Error in *alt-display2d*.
Messge: Condition designator ((MLABEL) $%O9 $X) is not of type (OR SYMBOL STRING
FUNCTION).
*alt-display2d* reset to nil.
-- an error. To debug this try: debugmode(true);
(%i10) x;
(%o10) x
39.2 Functions and Variables for alt-display
- Function: define_alt_display (function(input), expr)
This function is similar to define: it evaluates its arguments
and expands into a function definition. The function is a
function of a single input input. For convenience, a substitution
is applied to expr after evaluation, to provide easy access to
Lisp variable names.
Set a time-stamp on each prompt:
(%i1) load("alt-display.mac")$
(%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([simp:false],
block([?\*alt\-display1d\*:false,?\*alt\-display2d\*:false],
?\*prompt\-prefix\*:printf(false,"~a~%",timedate()),
?displa(x)))
(%i4) set_alt_display(1,time_stamp);
(%o4) done
2014-01-07 13:41:50-05:00
(%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.
- 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
- 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>
- 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}$${{x}\over{y^2+x^2}}$$
- 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
- 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.
- 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.
- 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
Emacs(8).
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
http://misc.flogisoft.com/bash/tip_colors_and_formatting and
http://www.tldp.org/HOWTO/Bash-Prompt-HOWTO/x329.html provide
information on how to use control strings to set the terminal colors.
This document was generated by Raymond Toy on May, 22 2016 using texi2html 1.76.
