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Order terms in symbolic poly converted to string

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Is there a way to control the order of the terms in a symbolic polynomial that has been converted to string?
E.g. the following
syms x
T=taylor(exp(x),order=3);
string(T)
results in
ans = "x + x^2/2 + 1"
and I would rather have it as 1+x+x^2/2 or the reverse order. I'll be putting this in the title of a plot so if there is some other way to automatically get the correct order in the title that would work equally as well.

Accepted Answer

Liam Ivers
Liam Ivers on 18 Jul 2024 at 1:13
Edited: Liam Ivers on 18 Jul 2024 at 1:17
Use the sympref function to change the display of the symbolic polynomial:
I noticed that the string function does not update with this change(A = "x + x^2/2 + 1"), but it does if you use the latex command (B = '1+x+\frac{x^2}{2}') which may look better for plot headings.
syms x
T=taylor(exp(x),order=3)
sympref('PolynomialDisplayStyle','ascend')
A = string(T)
B = latex(T)
titletext = ("$" + latex(T) + '$')
title(titletext,Interpreter='latex')
  2 Comments
Sam Chak
Sam Chak on 18 Jul 2024 at 1:36
@Ethan Duckworth, Consider trying this "what-you-see-is-what-you-get" direct approach.
sympref("PolynomialDisplayStyle", "ascend");
syms x
T = taylor(exp(x), order=3)
T = 
titletext = ("$" + latex(T) + '$');
fplot(T), grid on
title(titletext, Interpreter='latex')
Ethan Duckworth
Ethan Duckworth on 18 Jul 2024 at 10:55
Weird that string(T) doesn't preserve the order of the terms, but that latex(T) does!

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More Answers (1)

James Tursa
James Tursa on 18 Jul 2024 at 1:26
Edited: James Tursa on 18 Jul 2024 at 1:50
Brute force if you need the string for some reason?
syms x
ex = taylor(exp(x),order=3)
ex = 
[C,T] = coeffs(ex)
C = 
T = 
terms = fliplr(C.*T)
terms = 
n = numel(terms);
s = char(terms(1));
for k=2:n
c = char(terms(k));
if( c(1)=='-' )
s = [s ' - ' c(2:end)];
else
s = [s ' + ' c];
end
end
s
s = '1 + x + x^2/2'
  1 Comment
Ethan Duckworth
Ethan Duckworth on 18 Jul 2024 at 10:54
Wholy cow! That works, but the shorter approach by @Liam Ivers is the one I accepted.

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