Mr. Sebastiaan Janssens

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14 years, 215 days
Utrecht University

MaplePrimes Activity

These are answers submitted by SGJanssens

Inside the first for-loop, the counter is not substituted into the procecedure definition. Currently, its only effect is that the procedure U is (re)defined 6 times. So, you can replace the first for-loop (including its contents) by

U := proc (k, h) options operator, arrow; 
   eval((diff(u0(x), [`$`(x, k)]))/factorial(k), x = 0) 
end proc;

Inside the second for-loop, something similar happens, but you also get an additional error because now U is defined in terms of itself, without an appropriate stopping condition. So, you can replace the second for-loop (including its contents) by

UU := proc (k, h) options operator, arrow; 
   (sum(sum(U(r, h-s)*U(k-r, s), s = 0 .. h), r = 0 .. k)+(k+1)*U(k, h))/m       
end proc;

(Note it is now called UU instead of U.) You can then evaluate UU at different arguments using a new for-loop, if you like.


I recommend looking in the Maple Programming Guide, in the Writing Packages chapter. (For Maple 2021, this is Chapter 11. For Maple 2018 it could be a different chapter number.) You can access your version via: Help Table of Contents - Manuals - Programming Guide.

There you find an extensive discussion of a few examples, smaller and larger, with source code also available in the Maple installation directory. The mechanics of building a library are also discussed in that chapter.



In your attachment, the cross product &x from the LinearAlgebra package is used.

If you run it without loading LinearAlgebra at the start, then &x from Physics[Vectors] is used and it works fine.



Matrix indexing is one-based, but Arrays let you choose the starting index at construction, so if you want you can do something like:

X := Array(0..1, 0..1, [[m[1,1], m[1,2]], [m[2,1], m[2,2]]]);


By the way, your code does not work because first you assign X to the proc, but then you re-assign X to the Matrix. By the time you evaluate X[0,0], Maple does not know about the proc anymore.


You could search Maple's help for "set" (or: type ?set at a worksheet prompt) and browse to the section "Modifying the elements".


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