MaplePrimes - Maple 2022 Posts and Questions

Why do subs, algsubs, and applyrule fail here?

GFY — Wed, 27 May 2026 09:19:15 Z

I would like to replace in eqn1 the occurrence of

E__b*I__b*Eval(diff(phi__1(x__1), x__1 $ 3), x__1 = L__1)

using the relation defined in bc1.

I have already tried subs, algsubs, and applyrule, but none of them successfully performed the substitution. What would be the recommended or more robust way to carry out this replacement in Maple?
The details are as follows: question527.mw.

Converting integral of sum into sum of integrals

GFY — Mon, 25 May 2026 08:47:04 Z

I am currently working with inert integrals and summations in Maple, and I encountered a difficulty when manipulating symbolic expressions. I would appreciate any suggestions or recommended approaches.

Specifically, I would like to achieve the following:

Convert an inert expression in the form of a “summation inside an integral” into an equivalent “sum of integrals” form.
In other words, transform expressions of the type:
Int(i=1∑nfi(x,t),x=a..b)
into
∑Int(fi(x,t),x=a..b)

while preserving the inert (Int) representation rather than evaluating the integral directly.

I have tried commands such as value, expand, convert, and related manipulation methods, but I have not yet found a suitable solution.
The integrand contains two variables, where xxx is the integration variable.
How can terms that are independent of xxx be automatically extracted outside the inert integral? For example, if the integrand contains coefficients or functions depending only on ttt, I would like Maple to rewrite
Int(g(t)f(x),x=a..b)
as g(t)Int(f(x),x=a..b)

without forcing evaluation of the inert integral.

Any recommendations, built-in commands, or pattern-based approaches would be greatly appreciated.
question525.mw

How to tweak a procedure, for use with Grid?

emendes — Fri, 22 May 2026 17:09:55 Z

Hi,

I need to run the following procedure a couple of million times. Although it works, Maple sometimes chokes for no apparent reason (if there is a reason, please let me know). I was wondering whether an expert could help me tweak the procedure (or possibly rewrite it) to achieve the best possible performance. I am planning to use Grid:-Map or, if possible, Threads:-Map.

generateNonlinearModelsPlus := proc(model::list,fullmodel::list,vars::list:=[x,y,z])
description "This function generates a list of all models with one more monomial from the full model":
local tab::table(),n:=nops(model),i,j,k:=1,ans,terms,aaa,allmoncoefThreads:
# local procedure
allmoncoefThreads := proc(f::list,vars::list)
description "This function finds the monomials multipled by their coefficients for each expression (equation) of a list.":
local n:=numelems(f),i,mon:=[seq](0,i=1..n),M,cc:=[seq](0,i=1..n),ans:
for i from 1 to n do
  cc[i]:=[coeffs](expand(f[i]),vars, 'M'):
  mon[i]:=[M]:
end do:
ans:=[seq](zip((ww,vv)->ww*vv,cc[i],mon[i]),i=1..n):
return(ans)
end proc:
# main part
ans:=zip((w,v)->expand(simplify(v-w)),model,fullmodel): # Find the monomials that are not in model
terms:=allmoncoefThreads(ans,vars): # Separate the monomials
#
for i from 1 to n do
   aaa:=model:
   for j from 1 to nops(terms[i]) do
       aaa[i]:=model[i]+terms[i,j]:
       tab[k]:=aaa:
       k:=k+1:
   end do:
end do:
tab:=convert(tab,list):
return(tab):
end proc:

Here is an example of how I run it:

model:=[y*alpha[1, 2], z*alpha[2, 3], x^3*alpha[3, 10] + x*alpha[3, 1] + alpha[3, 0]]:

fullmodel:=[x^3*alpha[1, 10] + x^2*y*alpha[1, 11] + x^2*z*alpha[1, 12] + x*y^2*alpha[1, 13] + x*y*z*alpha[1, 14] + x*z^2*alpha[1, 15] + y^3*alpha[1, 16] + y^2*z*alpha[1, 17] + y*z^2*alpha[1, 18] + z^3*alpha[1, 19] + x^2*alpha[1, 4] + x*y*alpha[1, 5] + x*z*alpha[1, 6] + y^2*alpha[1, 7] + y*z*alpha[1, 8] + z^2*alpha[1, 9] + x*alpha[1, 1] + y*alpha[1, 2] + z*alpha[1, 3] + alpha[1, 0], x^3*alpha[2, 10] + x^2*y*alpha[2, 11] + x^2*z*alpha[2, 12] + x*y^2*alpha[2, 13] + x*y*z*alpha[2, 14] + x*z^2*alpha[2, 15] + y^3*alpha[2, 16] + y^2*z*alpha[2, 17] + y*z^2*alpha[2, 18] + z^3*alpha[2, 19] + x^2*alpha[2, 4] + x*y*alpha[2, 5] + x*z*alpha[2, 6] + y^2*alpha[2, 7] + y*z*alpha[2, 8] + z^2*alpha[2, 9] + x*alpha[2, 1] + y*alpha[2, 2] + z*alpha[2, 3] + alpha[2, 0], x^3*alpha[3, 10] + x^2*y*alpha[3, 11] + x^2*z*alpha[3, 12] + x*y^2*alpha[3, 13] + x*y*z*alpha[3, 14] + x*z^2*alpha[3, 15] + y^3*alpha[3, 16] + y^2*z*alpha[3, 17] + y*z^2*alpha[3, 18] + z^3*alpha[3, 19] + x^2*alpha[3, 4] + x*y*alpha[3, 5] + x*z*alpha[3, 6] + y^2*alpha[3, 7] + y*z*alpha[3, 8] + z^2*alpha[3, 9] + x*alpha[3, 1] + y*alpha[3, 2] + z*alpha[3, 3] + alpha[3, 0]]:

vars:=[x,y,z]:

ans:=generateNonlinearModelsPlus(model,fullmodel,vars)

Many thanks.

How to get a date from a Julian Day Number

Jno — Sat, 04 Apr 2026 16:02:41 Z

Hi,

Is there a way to get a date from a Julian Day Number in Maple? I can easily calculate a Julian Day Number in Maple, but sometimes I need to go in the other direction. I have searched for a solution. Google AI has suggested a couple solutions, but the Maple commands it gives don't seem to exist (certainly not in Maple 2022.2).

Thanks,

John

Delta symbol in name

Tycho Brahe — Thu, 19 Mar 2026 01:39:14 Z

I am trying to use the symbol Delta in front of a symbol to denote a change in the variable in Maple 2022.For exmaple Q':=Q+Delta_Q; But I can't figure out how to denote it: Delta_Q does not seem to work as it displays a literal "Delta_Q".

Trouble browsing large vector or matrix

Jno — Tue, 17 Mar 2026 00:06:10 Z

Hi,

I was running Maple 2022.2 on Windows 11 and now I am using Linux Mint. I ran into something today that doesn't work as expected on LM. I thought it did on Windows, but now I am not so sure.

At any rate, I am unable to browse large vectors or matrices with more than 10001 rows. I looked for a setting that lets me change it, but I can't find one. The data is there--I can plot it and export it, but I can't browse it.

Any thoughts? Thanks.

Cheers,

Jno.