Re: [Maxima-discuss] texput, \frac, and diff

[Leo B. <Leo...@um...>]

On Tue, Aug 29 2023, Eduardo Ochs <edu...@gm...> wrote:

> Hi list,
>
> In this message
>
>   https://sourceforge.net/p/maxima/mailman/message/37875807/
>
> Leo Butler showed a texput that makes tex1 use \frac instead of \over.
> But I just noticed that when I use "display2d:'emaxima$" his texput
> makes d/dx be displayed as 1/x... and I don't know how to debug that.
> Help, please?

emaxima is a red herring.

The correction is to bind simp to false in the body of the lattex-er:

   texput("/", lambda([r],
       block([n,d,simp:false],
             n:num(r),
             d:denom(r),
             printf(false,"\\frac{~a}{~a}",tex1(n),tex1(d)))))$

The function tex-d (src/mactex.lisp) creates a quotient with d in
numerator and denominator. If simp=true, then that common factor is
cancelled. Hence the puzzling form of output and your question. 

With that change:

(%i12) tex('diff(f(x),x)) $
$$\frac{d}{d\,x}\,f\left(x\right)$$

(%i13) tex('diff(f(x,y),x,1,y,1)) $
$$\frac{d^2}{d\,x\,d\,y}\,f\left(x , y\right)$$

Best,
Leo

>
> Here is the code:
>
>   load("/home/edrx/bigsrc/maxima/interfaces/emacs/emaxima/emaxima.lisp")$
>   display2d:'emaxima$
>   a/b;
>   'diff(y,x);
>   texput("/", lambda([r],
>       block([n,d],
>             n:num(r),
>             d:denom(r),
>             printf(false,"\\frac{~a}{~a}",tex1(n),tex1(d)))))$
>   a/b;
>   'diff(y,x);
>
> When I run it in a REPL I get this:
>
>   (%i1)
> load("/home/edrx/bigsrc/maxima/interfaces/emacs/emaxima/emaxima.lisp")$
>
>   (%i2) display2d:'emaxima$
>
>   (%i3) a/b;
>   (%o3) {{a}\over{b}}
>   (%i4) 'diff(y,x);
>   (%o4) {{d}\over{d\,x}}\,y
>   (%i5) texput("/", lambda([r],
>       block([n,d],
>             n:num(r),
>             d:denom(r),
>             printf(false,"\\frac{~a}{~a}",tex1(n),tex1(d)))))$
>
>   (%i6) a/b;
>   (%o6) \frac{a}{b}
>   (%i7) 'diff(y,x);
>   (%o7) \frac{1}{x}\,y
>   (%i8)
>
> Thanks in advance!
>   Eduardo Ochs
>
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