composition of functions

07222014, 01:23 AM
Post: #1




composition of functions
Is there a command for the composition of two functions, f and g, in CAS? There is f@@g in xcas, but I do not seem to get it to work in the Prime.


07222014, 02:17 AM
(This post was last modified: 07222014 02:19 AM by Mark Hardman.)
Post: #2




RE: composition of functions
(07222014 01:23 AM)Alberto Candel Wrote: Is there a command for the composition of two functions, f and g, in CAS? There is f@@g in xcas, but I do not seem to get it to work in the Prime. Try something along the lines of: f(x):=√(x²1) g(x):=4*x The composition of the two functions is simply: f(g(x)) HTH Ceci n'est pas une signature. 

07222014, 03:54 AM
Post: #3




RE: composition of functions
Thank you Mark. But I was looking for something like that on page 12 of this Xcas/giac tutorial


07222014, 09:51 AM
Post: #4




RE: composition of functions
In Xcas, @ does function composition, not @@, @@ is for composition power.


07222014, 03:44 PM
Post: #5




RE: composition of functions
(07222014 09:51 AM)parisse Wrote: In Xcas, @ does function composition, not @@, @@ is for composition power. Yes, thanks, I should have written f@g for the composition and f@@n for the composite of f with itself n times. The prime accepts f@g, but it seems to return a function like (x,y)>(f(x),g(y)) (if f and g are 1 variable functions). 

07222014, 04:07 PM
Post: #6




RE: composition of functions
Please give an example.


07222014, 09:14 PM
Post: #7




RE: composition of functions  
07222014, 11:11 PM
Post: #8




RE: composition of functions
(07222014 09:14 PM)Alberto Candel Wrote:(07222014 04:07 PM)parisse Wrote: Please give an example. The CAS is providing an intermediate solution to the composition. If you execute: simplify(f@g) You get the expected result: (_(x))>_(x)²+2*_(x)+1 Ceci n'est pas une signature. 

07232014, 02:41 PM
(This post was last modified: 07232014 03:32 PM by Alberto Candel.)
Post: #9




RE: composition of functions
That works, thanks.
But it would be better without the simplify part. [edit] Actually, if you define k:=f@g, then k(x)=x^2+2*x+1, without the simplify.[/edit] 

07232014, 06:23 PM
Post: #10




RE: composition of functions
You can also type (f@g)(x). Note that f@g is a function, not an expression.


07232014, 09:21 PM
Post: #11




RE: composition of functions  
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