# (f(g(x)) in Sage? How?

Hi everybody ! I am a total beginner and want to learn to use Sagemath. How do I write a script that calculates the following (f(g(x)). I thank you in advance for helping me. Ulf

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You can write f(g(x)) in Sage. In your situation: what is f? what is g?

( 2019-07-14 03:48:47 -0500 )edit

Thanks! How do I define f(x) and g(x). I guess you have to tell SAGE what these functions are first?

( 2019-07-16 02:26:34 -0500 )edit

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You may use compose as in the following sample:

sage: h = compose(sin, cos)

sage: h(1.23456)
0.323982971162499

sage: sin(cos(1.23456))
0.323982971162499

sage: plot( compose(sin, cos), (0, pi) )
Launched png viewer for Graphics object consisting of 1 graphics primitive


(The explicit composition works, of course, but sometimes one needs the composition without passing through the explicit evaluation, as in the above plot example.)

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Thanks! So I just write h = compose(x^2,x^3) and then I can put in values?

( 2019-07-16 02:29:31 -0500 )edit