Direct substitution vs "subs" method

dsejas
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5426 ●4 ●44 ●121

Suppose I define

var('a b c')
formula = a^2 + 5*b + c

Then I would like to substitute some values, like a=2, b=2 and c=4. As far as I'm aware, there are two options to do this:

formula(a=2, b=2, c=4)

and

formula.subs(a=2, b=2, c=4)

In this particular case, is there any difference between this two options? Is there any difference in some other case(s)?

Thanks in advance for you answers!

There basically no difference. Indeed, if you look at the source code of the __call__ method of formula by typing:

sage: formula.__call__??

you can see that there is :

return self._parent._call_element_(self, *args, **kwds)

So, if you look at the _call_element_ element of the parent of formula (which is the symbolic ring) by typing:

sage: SR._call_element_??

besides some deprecation warnings, there is:

return _the_element.subs(d, **kwds)

Comments

Thank you very much for your answer, @tmonteil. This is exactly what I was expecting when I asked the question!

dsejas ( 5 years ago )

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