How to avoid ^- in maxima output? (Leo Butler)

Leo,

thanks a lot for the great help.

I did not examine the code yet but I see that this might be the solution of
the given problem and I am glad to see that such problems can be handled on
the Maxima side. We would like to avoid any modification of existing Maxima
installations and rather load the scripts from our plugin directory. I guess
that the search path for maxima can be extended accordingly.

Best regards, Martin

> -----Urspr?ngliche Nachricht-----
> Von: Leo Butler [mailto:l_butler at users.sourceforge.net]
> Gesendet: Donnerstag, 24. Oktober 2013 16:48
> An: Martin Kraska
> Cc: maxima at math.utexas.edu
> Betreff: Re: [Maxima] How to avoid ^- in maxima output? (Leo Butler)
> 
> >   From: Martin Kraska <kraska at fh-brandenburg.de>
> >   Date: Thu, 24 Oct 2013 01:09:02 +0200
> >
> >   Leo, thanks for the response ( and Robert, for your's as well).
> >
> >   Other examples are
> >
> >   "e^-cos(x)/b", misunderstood as e^{-cos(x)/b},
> >   "e^-c/b" , misunderstood as  e^{-c/b}
> >
> >   1d versions which would be understood correctly, are:
> >   "e^(-cos(x))/b"
> >   "e^(-c)/b"
> >
> >   Thus, how can Maxima be forced to bracket the unary minus operator in
1d
> >   output?
> 
> Ok, I do see what you want. My suggestion is basically what RJF and Robert
> were hinting at. What you can do is use Maxima's ability to apply
> transformation rules to expressions to re-write the expression before it
is
> displayed. Here is what I mean:
> 
> (%i10)  (to_mx_display(), kill(all), load("smath.mac"))$
> 
> (%i1) [e^-4, %e^-t/d, %e^-cos(x)/y];
> (%o1) [1/e^4,%e^-t/d,%e^-cos(x)/y]
> 
> (%i2) to_sm_display();
> (%s2) %s                                  <-- change outchar for different
display mode
> 
> (%i3) [e^-4, %e^-t/d, %e^-cos(x)/y];
> (%s3) [e^{-4},%e^{-t}/d,%e^{-cos(x)}/y]   <-- desired output
> 
> (%i4) to_mx_display();
> (%o4) %o                                  <-- revert to maxima's standard
1d display
> 
> (%i5) %s3;
> (%o5) [1/e^4,%e^-t/d,%e^-cos(x)/y]        <-- the expr in %s3 is valid
maxima
> code
> 
> where
> 
> smath.mac:
> /* -*- Mode: maxima; Package: MAXIMA -*- */
> /*
> ;; Copyright Leo Butler (leo.butler at member.fsf.org) 2013 ;; Released under
the
> terms of GPLv2 */
> 
> matchdeclare([sm_x],true,sm_y,lambda([e],if is(numberp(e) and e<0 and
e#-1)
> or is(not(atom(e)) and op(e)="-") then true else false));
> defrule(sm_exp_to_power,sm_x^sm_y,sm_x^{sm_y});
> sm_rules:['sm_exp_to_power];
> 
> load("smath.lisp")$
> 
> /* end of smath.mac */
> 
> 
> smath.lisp:
> ;; -*- mode: lisp -*-
> ;; Copyright Leo Butler (leo.butler at member.fsf.org) 2013 ;; Released under
the
> terms of GPLv2
> 
> (in-package :maxima)
> 
> (defvar *displa* (symbol-function 'displa)) (defvar *maxima-outchar*
$outchar)
> (defvar *smath-outchar* '$%s) (defvar $sm_rules)
> 
> (defun $smath_displa (form &optional (sm-rules $sm_rules))
>   "Display FORM by APPLY1-ing the rules in SM-RULES to the EXPR in FORM."
>   (declare (special $sm_rules *alt-display1d*))
>   (let ((rules (cdr sm-rules))
>         (*alt-display1d* nil)
>         (expr (third form)))
>     (funcall *displa*
>              (list (first form) (second form)
>                    (dolist (rule rules expr)
>                      (setf expr (mfuncall '$apply1 expr rule)))))))
> 
> (defun $to_sm_display ()
>   "Set-up Maxima to use SMATH_DISPLA to display output."
>   (declare (special *alt-display1d* $outchar *smath-outchar*))
>   (setf *alt-display1d* (symbol-function '$smath_displa))
>   (setf $outchar *smath-outchar*))
> 
> (defun $to_mx_display ()
>   "Return Maxima to use standard DISPLA for 1d output."
>   (declare (special *alt-display1d* $outchar *maxima-outchar*))
>   (setf *alt-display1d* nil)
>   (setf $outchar *maxima-outchar*))
> 
> 
> ; end of smath.lisp
> 
> Leo