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.

Risposta accettata

Liam Ivers
Liam Ivers il 18 Lug 2024
Modificato: Liam Ivers il 18 Lug 2024
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 Commenti
Sam Chak
Sam Chak il 18 Lug 2024
@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 il 18 Lug 2024
Weird that string(T) doesn't preserve the order of the terms, but that latex(T) does!

Accedi per commentare.

Più risposte (1)

James Tursa
James Tursa il 18 Lug 2024
Modificato: James Tursa il 18 Lug 2024
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'

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