How can I order the factors when using the sym and latex functions?

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MortenJ
MortenJ 2016-12-26
评论： MortenJ 2016-12-30
Hi,
is it possible to control the order of the factors when using the sym and latex-functions?
E.g.
str = (5/8)*x;
out = latex(sym(str));
% produces out='\frac{5\, x}{8}'
% corresponding to (5*x)/8 and not (5/8)*x (='\frac{5}{8}x') as desired
I know these are mathematically identical, but I use the output for educating students and for them the second expression is easier to understand. I have thousands of expressions so need to find a way to do this automatically.
Thank you in advance, Morten

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采纳的回答

Walter Roberson
Walter Roberson 2016-12-29
No, the Symbolic Toolbox does not offer an way of giving preferences on how the terms are to be formatted or ordered.
In this particular case the work-around would be
out = [latex(coeffs(str,x)),latex(x)]
coeffs() with two outputs is generally useful for formatting terms of a polynomial. For non-polynomial expressions, you might need to start using children() .
Unfortunately, in order to find out the basic operation that you are getting the children of, you need to pop into the symbolic engine:
feval(symengine, 'op', str, 0)
which in this case would get you sym('_mult'); you might also see _power or _plus or _not or _less or _leequal or _SYM_equal or _or

更多回答（1 个）

Ankitha Kollegal Arjun
Morten,
You could try the following:
1. Factorize the required symbolic expression using factor(). (result will be a symbolic vector)
2. Use the latex() function on each element of the above symbolic vector and concatenate the results to obtain the desired latex format.
>> syms x
>> str = (5/8)*x;
>> temp = factor(str);
>> out = [latex(temp(1)) latex(temp(2))]
out =
\frac{5}{8}x
  1 个评论
MortenJ
MortenJ 2016-12-30
Works great, thanks. I realized I also had to deal with a lot of other equation-formats, so picked the suggestion by Walter below, which was able to deal with those as well, but thanks for helping out.

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