For a maths project I am currently using the CAS Maxima (wxMaxima). As the project is almost finished I would like to remain with Maxima, but there is one problem left:
The issue is that I have to convert a certain polynomial P by making all its coefficients positive. I.e. adding up the absolutes of all coefficients (but not taking the absolute value of the whole polynomial), for example
P(...)=-15x^3+3y^2-4x^2
turns to
P'(...)=15x^3+3y^2+4x^2
I could not find an implemented function that would help me with this. And could not find a solution by implementing it with a map function. Do you know a way to solve this issue?
Thank you for your help!
Jonas
You can calculate a sum of absolute values:
P:-15*x^3+3*y^2-4*x^2;
P2:sum(abs(args(P)[i]),i,1,length(args(P)));
>> 3*y^2+15*x^2*abs(x)+4*x^2
(unfortunately, here is abs(x) but you can use subst(x,abs(x),P2))
The same with map:
P2:map(abs,P);
Or convert an expresstion to string and replace "-" to "+":
s:string(P);
s2:ssubst("+","-",s);
P2:eval_string(s2);
>> 3*y^2+15*x^3+4*x^2
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Example code:
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Can someone explain to me how these two functions are equivalent?
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