why

expr:=1-3*y;
patmatch(expr, b::integer - a::integer*y,'la');

gives false but

expr:=1-3*y;
patmatch(expr, b::integer + a::integer*y,'la');

gives true?

Should one then use `+` for matching with `+` and `-`? This result was a little confusing to me. 

It is actually good that it behaves this way. Makes it easier to write the pattern (less cases to cover). But I would have expected both to return true, that is all.

I found I can start Maple itself 2 times on my windows PC. (I think my license allows max of 2, but I could be wrong).

I want to run a program which takes long time. But I want to use Maple at same time.

Which is the recommended approach:

1) Start 2 separate Maple applications. Use one to run the long program, and then I can use the second Maple for other things while the first is running)

2) Start one Maple, but set the "How should Maple handle the create of new Math engine" to "Ask me each time"

for me, choice 1 seems more safe. But thought to ask if there is something else I should consider when making which choice to pick.

Update

Found out that actually when clicking on Maple icon, I was not starting a new Maple at all. It was just starting a new worksheet using the currently running Maple ! This is confusing. With Mathematica, clicking on its icon actually starts a new complete separate Mathematica application. Not a new notebook using the currently running Mathematica.

So the question I have now is: Can one start 2 separate Maple applications on windows?  And if so, how?

is there a way  for a proc() in a parent module to call an exported proc in a child module, without having to use long form of the call    child:-child_proc() and just do child_proc()?  Here is an example

A:=module()
  option package;
  export foo;
  local B; #child module

  B:=module()     
     export boo;
     boo:=proc()
        print("in B:-boo()");
     end proc;
  end module;
  
  foo:=proc()
     B:-boo();  #how can one just type  boo() here?
  end proc;
end module;

B:-foo(); now works ok. But I'd like to just use  boo() and not B:-boo() since the name of the child module is too long. 

I can't figure how to do it. I can't use with(B) in the parent, Maple complains. 

When a child proc calls a parent local proc using parent_module:-parent_proc(), Maple gives an error. But when the child calls the parent local proc using just parent_proc() it works. Why is that?

parent_module:=module()
 
 local child_module;
 local parent_proc;

 export parent_entry;

 child_module:= module()
    export child_entry; 
    child_entry :=proc()
     #parent_module:-parent_proc(); #this fails
     parent_proc(); #this works
    end proc;
  end module;

 #local
 parent_proc :=proc()
   print("insider parent proc");
 end proc;

 #public
 parent_entry :=proc()
   child_module:-child_entry();
 end proc;
end module;

parent_module:-parent_entry();
              "insider parent proc"

but the other way, (the commented code above) gives

parent_module:-parent_entry();
Error, (in child_entry) module does not export `parent_proc`

my main module is getting big. I want to break it to main module, and submodule. But now everything is in the same .mpl file. I'd like to put the sub module in seperate mpl file. I do not know the syntax to do this and how to do it. I looked at the programming guide chapter 8.

Currently in main_module.mpl, lets say I have this

main_module:=module()
 option package;
 local C; 
 local sub_module;
 export main_entry;

 C:=99; #see if this can be "seen" from child module

 sub_module:= module()
    export main_entry;
    main_entry :=proc()
     print("In main_module:-sub_module:-main_entry(), C=",C):
    end proc;
  end module;
 
 main_entry :=proc()
   print("in main_module:-main_entry()"):
   sub_module:-main_entry();
 end proc;
end module;

Now main_module:-main_entry(); gives

                 "in main_module:-main_entry()"
       "In main_module:-sub_module:-main_entry(), C=", 99

I'd like to move the code of the submodule to another .mpl file. So I end up with two files, like this

# main_module.mpl
main_module:=module()
 option package;
 local C; 
 local sub_module;
 export main_entry;

 C:=99; #see if this can be "seen" from child module

 main_entry :=proc()
   print("in main_module:-main_entry()"):
   sub_module:-main_entry();
 end proc;
end module;

And

#sub_module.mpl
sub_module:= module()
    export main_entry;
    main_entry :=proc()
     print("In main_module:-sub_module:-main_entry(), C=",C):
    end proc;
 end module;

But when I do this, I can't call main_module:-main_entry(); since it gives error

Error, (in main_entry) `sub_module` does not evaluate to a module
I do not want to make sub_module a separate package. I want it to remain a sub module for the main module, so it can only be seen by the main module and no one else.

So logically sub_module is a child of main_module, but physically I want to put them in separate files to make it easier to modify.

I use plain text files for everything and use Maple to load the packages and test.

How does one go about doing this? How would this be done for the above example?

I tried $include "sub_module.mpl"; but it gives error.

main_module:=module()
 option package;
 local C; 
 local sub_module;
 export main_entry;

 C:=99; #see if this can be "seen" from child module
	
 $include "sub_module.mpl";

 main_entry :=proc()
   print("in main_module:-main_entry()"):
   sub_module:-main_entry();
 end proc;
end module;

Where the file "sub_module.mpl" contains the code for the submodule I want to insert at that location. When I read "main_module.mpl" Maple gives error

read "main_module.mpl";

Error, on line 10, syntax error, unexpected string:
 $include "sub_module.mpl";

This is too advanced for me. I am still learning module and package use in Maple.

thanks