MaplePrimes - answers and comments on Question, Fraction Display

No simple way

Preben Alsholm — Wed, 02 Jan 2013 05:19:07 Z

Automatic simplification turns (5+3*x)/15 into 1/3 + x/5.
Try

'(5+3*x)/15';

Thus any conceivable simplification procedure used on 1/3 + x/5 would fail to produce what you want unless it produces output like e.g.

``(5+3*x)/15;
(5+3*x)/``(15);

maple distributes numbers

roman_pearce — Wed, 02 Jan 2013 07:40:57 Z

Maple automatically applies the distributive law "a*(x+y) = a*x+a*y" for numbers. For programming purposes, e.g. fraction free algorithms, you can get a numerator and common denominator from the numer and denom commands. E.g.:

f := 1/3 + x/5;

n := numer(f);

d := denom(f);

However if you form the fraction n/d it will again produce 1/3+x/5.

Reference

Markiyan Hirnyk — Wed, 02 Jan 2013 10:36:07 Z

It was asked and answered few times. See http://www.mapleprimes.com/questions/132118-Express-Algebraic-Expressions-As-A-Single#comment132121 . PS. This link can be found by the "fraction" search in MaplePrimes at the top of this page. PPS. Compare the answer by Preben Alsholm with the code by Joe Riel: > expr := 1/3+(1/5)*x; > makefrac := (`@`(``, numer))/(`@`(``, denom)): makefrac(expr); (5 + 3 x)/(15)

Possible variant

Kitonum — Wed, 02 Jan 2013 12:36:11 Z

f := 1/3 + x/5:

numer(f)/convert(denom(f), symbol);

decoupling automatic simplification from display

Alejandro Jakubi — Mon, 13 May 2013 11:15:56 Z

The OP's question is about the display of a fraction, rather than the computation of a fraction which is unavoidably affected by automatic simplification rules. Now, if a pair of expressions (C,D) were handled, one for computation (as usual) and another one for display, even when C is a fixed representative within a class of mathematically equivalent expressions set by these automatic simplification rules, it could become possible to "compute" D as the display expression associated with any computational expression of this equivalence class, so that it displays in the desired form.

For pure display purposes, a demonstration procedure as in this sketch may be enough in the Standard GUI:

An additional step, copy-pasting the computational expression was described here by using the undocumented procedure Typesetting:-mcomplete, so that a variation of the above demonstration procedure could be used for the generation of its argument:

Here the last input line was generated by copying the output and pasting as intput.

This is a hint of the things that I think could be done by decoupling computation from display when using a pair of expressions, instead of only one.

The output of

Markiyan Hirnyk — Wed, 02 Jan 2013 14:42:24 Z

> evalf(expand(%)); 5./15 + 3. x/15