Hola,
is there a way to convert symbolic expression to proper functions?
E. g. s = sin(x) into x |--> sin(x)
So far I've been using f(x) = s(x), however, deprection warnings occur:
DeprecationWarning: Substitution using function-call syntax and unnamed
arguments is deprecated and will be removed from a future release of Sage; you
can use named arguments instead, like EXPR(x=..., y=...)
Does it answer the question ?
sage:s=sin(x)
sage: s
sin(x)
sage: f=s.function(x)
sage: f
x |--> sin(x)
sage: s = sin(x)
sage: f(x) = s
sage: f
x |--> sin(x)
No deprecation warning! What's going on here is that s(x) was really trying to evaluate your symbolic expression s at the point x - which happened to be a variable, but is still deprecated. If you use the transitive property, the above is just saying
sage: f(x) = sin(x)
which is what you want, as opposed to
sage: f(x) = sin(x)(x)
in your first attempt, which is perhaps ambiguous.
You could use `s.variables()` and `s.variables()[0]` to find out what the variable was. Only if you are sure there is only one variable - expressions like `a*sin(x)` wouldn't work, even if `a` is a "constant", since Sage can't tell the difference without the function notation. Also, the "obvious" thing to do `f(s.variables()[0]) = s`, or even to name that and then plug it in, doesn't work because of the way the preparser works. In short, it's mostly not worth the effort.
Asked: 2012-05-20 06:52:44 +0200
Seen: 1,751 times
Last updated: May 21 '12
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