When running this

expr:=5;
for item in expr do
    print(item);
od;

it prints 5 as expected. When when running

expr:=I;  (* NOTICE this is complex  I not the number 1 *)
for item in expr do
    print(item);
od;

it prints the number 1 and not I

I am sure there is a good reason why this happens.

But what should one do to insure they get the complex I in the second example when iterating over a sum of numbers, which in this example happened to be just one number who is complex? I know I can add explicit check to avoid this edge case.

The problem is that I want to iterate of sum of iterms, One or more of them can be complex I. (it is a result of doing series expansion of function at infinity, and I want to iterate over each term in the series one by one).

expr:=9+I:
for item in expr do
    print(item);
od;

Gives   9,1   and not 9,I

While

expr:=a+I:
for item in expr do
    print(item);
od;

does now give exected output   I,a  and not 1,a

What should one do to insure the for loop always get each term in the sum, even if it is complex?

I can't check the item inside the loop, because by then it is too late as the compelx I is lost already.

Is there a better way to iterate over sum of terms and look at each term as is and not lose the complex I in the way?

Maple 2022.1

Update 

For now, I am doing this hack. Since the input is always a sum (with + or - terms), then I convert the input to string, split on delimitors and then parse the entries back to Maple and now it is a list so I can iterate over each term. 

expr:=I+3:
String(expr):
StringTools:-SubstituteAll(%,"+","|+"):
StringTools:-SubstituteAll(%,"-","|-"):
StringTools:-Split(%,"|"):
map(Z->parse(Z),%):
for item in % do
    print(item);
od;

And when expr is

expr:=1+5*I+sin(x)-sqrt(8)*I-a;

It is a hack, but I could not find a relaible way to iterate over each term in the sum of terms without losing the complex I if one term was complex. I need to test this more. It is meant to work only on expression which is sum of terms, which is where I will use it.

Compare the output of the above for expr:=1-I;

The for loop gives 1,-1  but the string hack gives 1,-I which is what I wanted.

Ofcourse the above could fail if there is a "-" or "+" inside the term itself (for example  1+I+sin(1-x) , but this do not happen for the cases I am using this for, which just looking at terms of series expansion around either zero or infinity. These will be just power series terms separated by "+" or possibly "-"

If there is better way do this, that will be great.

When I enter x-y Maple echoes x-y. When I enter y-x Maple echoes y-x. When I enter b - a Maple echoes  b-a.  But when I enter a-b Maple echoes -b + a

I fiind this promotion of negatives, which also occurs in more complicated expression, somewhat confusing.

Is there any description of the rules Maple uses and perhaps ways of controlling them?

Maple allows to extract, manipulate, and optimize equations from a MapleSim model. Code can be generated from the equations in various programming languages. To verify the code, C code can be imported back into the original MapleSim model and compared to the model.

This verification step is not an everyday task, but it is advisable before the code is used elsewhere (e.g., in a controller). This post summarizes helpfull links and provides an additional example with equations that are too large to be efficiently verified by code review.

Comparison to a physical model is demonstrated here on an older version of MapleSim (~2015). In newer versions the import has changed (basics are described in Tutorial 6.6: Using the External C Code/DLL Custom Component App). An external C compiler must be set-up to make the import work.

The attached MapleSim model verifies against an optimized custom component. Instead of manually entering and modifying the code as described in the Tutorial 6.6, the model uses a Maple worksheet that programmatically generates C code from Maple equations and modifies the C code (sets C definitions and parameters) to be usable for MapleSim’s External C/Library Block App.

The Maple worksheet to generate and modify C code has been improved in many details with support from MaplePrime users for which I would like to express my thanks.

C_code_generation_of_optimised_code_for_MapleSim.mw

C_code_generation_of_optimised_code.msim

Why doesn't 

produce anything?

I guess this is some kind of tricky function since for non-integer x it seems not to correspond to a real number.

This came up for me when thinking about a sequence n(c^n), where |c|<1.

Is there some way to plot the values of a sequence? 

Suppose H is a 2*2 matrix and (x0,y0) is the center of an ellipse. We want to draw the ellipse in form of (x-x0,y-y0)H(x-x0,y-y0)^T. 

Equivalently, suppose we use variable P to show both x and y in the vector form. How is it possible to draw P^T H P? I would be thankful if you could give me and example.

Download PDE_integral.mw

Hey guys im using maple 2022 with last version of Physics package (version 2022) , I know my question might be stupid but in the following expression 

restart;
with(Physics[Vectors]);
Setup(mathematicalnotation = true);
with(Physics);
Setup(op = {I__b, I__s, Omega, `ω_`});
eval(I__b . (diff(`&omega;_`(t), t)), {I__b = <<I__1 | 0 | 0>, <0 | I__2 | 0>, <0 | 0 | I__3>>, `&omega;_`(t) = <omega[1](t), omega[2](t), omega[3](t)>})

I want to get the following as result

but I keep getting the unevaluated one as follows

What am I doing wrong here, 

thanks in advance

i have a problem in an optimzation problem. in the problem using NLPSolve to find the minimum, i have an integration which i use the Int command to be solved in the optimization process, but this error occures: Error, (in Optimization:-NLPSolve) could not store Int(..) in a floating-point rtable 
please help to solve the problem, tnx in advance

Download LinearLog-A-Bayesian_1.mw

"Warning, unable to evaluate 2 of the 6 functions to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct" How to fix it?

mww.mw

Hi, 

everyone! I want to define a function with a constant (i. e., 1/3 in the following figure). Actually, I tried it by "proc" or "piecewise", but it does not work.  So could you give me some suggestions? Thanks a lot!

g:=proc(n+1/4)
  if (n=0) then 1
    else 0
  end;
end proc;

How do i solve nonlinear coupled orinary differential equation with boundary conditions?

restart;
alias(u = u(x, y, z, t), f = f(x, y, z, t));
                              u, f
u := (diff(f, y, x, x, x, x))*f^4-(diff(f, x, x, x, x))*(diff(f, y))*f^3-4*(diff(f, y, x, x, x))*(diff(f, x))*f^3+8*(diff(f, x, x, x))*(diff(f, x))*(diff(f, y))*f^2-4*(diff(f, x, x, x))*(diff(f, y, x))*f^3+12*(diff(f, y, x, x))*(diff(f, x))^2*f^2-36*(diff(f, x, x))*(diff(f, x))^2*(diff(f, y))*f+24*(diff(f, x, x))*(diff(f, x))*(diff(f, y, x))*f^2-6*(diff(f, x, x))*(diff(f, y, x, x))*f^3+6*(diff(f, x, x))^2*(diff(f, y))*f^2-24*(diff(f, x))^3*(diff(f, y, x))*f+24*(diff(f, x))^4*(diff(f, y))+2*(diff(f, y, x, t))*f^4-2*(diff(f, y, x))*(diff(f, t))*f^3-2*(diff(f, x, t))*(diff(f, y))*f^3+4*(diff(f, x))*(diff(f, y))*(diff(f, t))*f^2-2*(diff(f, x))*(diff(f, y, t))*f^3-3*(diff(f, z, x, x))*f^4+3*(diff(f, x, x))*(diff(f, z))*f^3+6*(diff(f, x))*(diff(f, z, x))*f^3-6*(diff(f, x))^2*(diff(f, z))*f^2;

Given a module A, it has a proc which is called to set some internal variable to some value. This proc is meant to be used as initialization of the module, and not meant to return anything (i.e. procedure vs. a function in other languages, where a procedure does not return anything, but a function does).

When this proc is called from outside, the result of the last assignment in the proc is returned back to the user since that is the default behavior.

Is there a way to prevent this, other than adding an explicit NULL at the end of this proc?  Adding : at the end the last statement or at the end of the proc did not prevent this.

Here is an example

restart;
A:=module()
  local r::integer;
  export set_r:=proc(r::integer)   
    A:-r:= r:   
  end proc:
end module:

Now when calling  A:-set_r(10), Maple will return back/echo back 10. But this is not something I want.

A:-set_r(10);

    10

To prevent this, currently I add NULL; at end of the proc, like this

A:=module()
  local r::integer;
  export set_r:=proc(r::integer)   
    A:-r:= r:   
    NULL;
  end proc:
end module:

and now

A:-set_r(10);

returns nothing. Well, it returns NULL but that is like nothing.

My question is, is there a better way to do this? Can one define a proc in Maple that returns nothing?

Maple 2022.1

Hi everyone

I am trying to get the maximum value (angle) for a function, which is a solution from a ODE. I tried evalf(max.. which I already thaught wouldnt work. 

After that I installed the package "DirectSearch", again with no success. 

Does anybody know what I am doing wrong or how I am going to get the maximum. I added the maple file with the direct seach attempt. 

Thank you in advance!

Please how  can I use getdata to extract only 200x2 of 208x2 matrix from maple to excel.

For instance I have:

Q:= ( seq( seq( plottools:-getdata(ans1[s1,3])[j,3],j=1..3), s1=1));

It returns  208x2,  200x2 200x2 matrices and I can't extract it using 

`<|>`( seq( seq( plottools:-getdata(ans1[s1,3])[j,3],j=1..3), s1=1));

because the matrices have different dimension. Please, how can make 208x2 matrix to 200x2?