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Substituting derivative in equation

asked 2015-07-29 20:21:39 +0200

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There is likely a simple way to solve this, but I cannot seem to find a way. Let say I have two functions, f(x,y) and g(x,y)




I want to be able to substitute a value for one of the derivatives. For example, if I have the equation x^2y+f.diff(x,1), I may want to substitute in the function g, so I have x^2y+g. I tried the following


And get an error that a keyword can't be an expression. Is there anyway to make this substitution?

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answered 2015-07-30 11:04:04 +0200

rws gravatar image

Multiplication needs *, it works for me:

sage: (x^2*y+f.diff(x,1)).subs(f.diff(x,1)==g)
x^2*y + g(x, y)
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Asked: 2015-07-29 20:21:39 +0200

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Last updated: Jul 30 '15