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Replies posted by Richard Stegeman

14 Replies
gdiepen
AIMMS Champ
gdiepenAIMMS Champ
asked in AIMMS Language
Question about index scope not being specified

After some investigations I found that there is a combination of things that make that this is not working:There is a really simple syntax error in the statement. There is a missing ‘)’ at the LHS of the assignment (look closely 😅). The new compiler in AIMMS is noticing this, but is not showing the error, because in such a situation it leaves the statement to be handled by the old compiler. Why the old compiler does not see this missing ‘)’ is not clear to me, nor what kind of statement it is trying to create as a result. Unfortunately, when you do add the missing ‘)’, the new compiler will pick up the statement but then give an error that there is no scope for ‘i_producer’. Having the running indices so deeply nested in the LHS is rather difficult for the compiler to deal with. But I do think that this is a bug in the compiler.One workaround for the latter problem is to place the assignment in a FOR loop.

812
Richard Stegeman
AIMMSian
gabiservidone
Administrator
gabiservidoneAIMMSian
published in AIMMS Language
Pipe Signs and Dollar Signs (Expected Changes for 4.97)Blog

Now that version 4.97 has been out for some time, it turns out that there is rather strange error where AIMMS suggests to change a $ to a | and when you have done that it asks to change the | to a $. 🤔This usually happens in a constructed set expression like:{ i $ condition(i) }If i is an unbounded index then this is indeed a deprecated usage of $ and you should use:{ i | condition(i) }The problem with the flipping warnings occurs when i is not an unbound index, as in:for i do    mySet := { i | condition(i) };endfor;Now if this is parsed as a constructed set, then the | is correct, but AIMMS should have given an error because i is already bound by the FOR statement. If parsed as an enumerated set (that is: a comma separated list of elements between curly braces) then the | should be changed to a $.So, if you do get in a situation where AIMMS asks to again and again change a $ into a | (and vice versa), please have a look at the statement and check whether you indeed want to re-use the

1905
Richard Stegeman
AIMMSian
R
ramkishore.krExplorer
posted in WebUI
Unable to navigate to the WebUI page using Chrome

Are both browsers showing this problem? If you click the small arrow next at the right side of the WebUI button, do you have an option to select Edge as the browser?  If so, what happens when you select Edge?  

985
gabiservidone
Administrator
gabiservidone
Administrator
gabiservidoneAIMMSian
published in AIMMS Language
Pipe Signs and Dollar Signs (Expected Changes for 4.97)Blog

There is no performance difference between writing either:x := a $ b; x := if b then a endif; x := a onlyif b;The resulting compiled expression is the same for all three.So it is indeed a matter of taste which one you prefer. Personally, I think the ‘if’ variant is much too verbose so I have preference for using the $.However there is a difference between using the ‘if’ expression and the ‘if’ statement. So writing if a then x:=b; else x:=0; endif; Is definitely performing worse than writing it as a single assignment like above. 

1905
Richard Stegeman
AIMMSian
C
AIMMS Partner
Casper van DijkAIMMS Partner
Highlighting occurrences of identifiersDeclined

I completely understand why you want this. I also sometimes miss it when working with AIMMS, as I am so used to it in other IDE’s (like Visual Studio).Unfortunately, the syntax editor that we are using is a third party editor and it does not support this feature so it will be really hard to get this in. Besides that, we have plans for a completely new model editing IDE so we don’t do that much new development in the current IDE. We will definitely look to this feature again when working on this new IDE.

3
276
gabiservidone
Administrator
C
AIMMS Partner
Casper van DijkAIMMS Partner
Auto-complete (Ctrl + spacebar) in the Find All window (Ctrl+Shift+F)Implemented

The name completion will work as from upcoming version 4.84.2

4
412
A
W
WRuijsscherExplorer
asked in AIMMS Language
Question regarding the union of sets

I just create a new topic on the suggested set construction. Perhaps interesting to read.Filling a set via the union of its subsets | AIMMS Community

2916
Richard Stegeman
AIMMSian
Richard Stegeman
AIMMSian
Richard StegemanAIMMSian
Cases and runtime libraries

@sandervlot  I forgot to mention that if you do not want to include a runtime library in the saving of a case, then you should set the ‘NoSave’ property on the library when creating it. Like this:me::SetAttribute(myLib, 'Property', "NoSave");Unfortunately this does not always help when you read back an older case file that has the library already in. Especially if the runtime library is not yet present during case read (because AIMMS then doesn’t know about the ‘NoSave’ property).If from now on you will just work with 4.77, you can forget about the above.  

7932
Richard Stegeman
AIMMSian
B
bjorn94Newcomer
asked in AIMMS Language
Why does the order of my set change?

Yes indeed, many of the more experienced AIMMS users work-around this problem by not using the fixed elements but instead use the StringToElement function. This moves the element-name-look-up from compile time to execution time, and that is what we also try to achieve in the current change that we make.  

2255
Richard Stegeman
AIMMSian
B
bjorn94Newcomer
asked in AIMMS Language
Why does the order of my set change?

This is indeed a rather unexpected ‘feature’ in AIMMS. Fixed quoted elements in the model text can have an effect on the ordering of elements in a set. Like in a statement elemParam := ‘elem1’;  or param(‘elem2’) := 3;If you really want a certain order in your set then use the order by attribute of the set. If you set this to ‘User’ then the assignments to the set will determine the set order (independent of any element being referenced somewhere else in the model text).In your example, I think that you can also make the set a subset of Integers. The problem with the ordering will then not be there.Perhaps good to know: at the moment we are working on this part of the compiler in AIMMS and we hope that this strange effect of fixed elements on the order of a set will be gone in the very near future. The ordering of the root sets (not a subset) in AIMMS will then by default behave like the ‘order by user’. 

2255
Richard Stegeman
AIMMSian
afattahi
afattahiEnthusiast
asked in AIMMS Language
How can I disable warnings of the Excel library (AXLL)

The recommended way to use the axll library is by placing all function calls in a block-onerror-endblock scope. In the onerror clause you can then catch each error or warning and decide what to with it. In this situation, check whether you are dealing with a warning (instead of error) and then call errh::markashandled() to make sure it is not propagated further.

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A
R
AIMMS Partner
RichardAIMMS Partner
posted in AIMMS Language
.nch (namechange) file and version control

The .nch file is used in several parts of AIMMS: Indeed: for cases. The most relevant now-a-days where most applications are WebUI based. Via the .nch file AIMMS knows how to map old names that are stored in a case onto the new names in the model. In the WinUI, for all references to identifiers stored in pages and user menus. Sometimes for libraries, which were readonly at the time the name change was done. The best advice for handling the .nch file when multiple developers are working on the same model is: Before committing: do a ‘commit namechanges’ in your model. This assures that WinUI and all (non-readonly) libraries are up-to-date with the latest namechanges.  Check whether new entries in the name change file are relevant for any cases that may exist at the users of your model. For example, if the name changes only refer to newly created identifiers they are kind of redundant after the ‘commit namechanges’ command. If you have a conflict: try to preserve the time stamp order. Reg

2424
sandervlot
AIMMS Partner
S
Stephen_PowickNewcomer
asked in AIMMS Language
Error - A definition cannot as a side effect change another identifier

This is indeed no longer supported in AIMMS. A definition of an identifier is not allowed to change any other identifier. In earlier AIMMS versions the error was not given while it should, and thus the result could be undefined.  Just wondering why the definition needs the StringToElement. Is the following not doing the same? { (tpehis,pe) | FormatString("%e",pe) = SubString(FormatString("%e",tpehis),1,4) + "-" + SubString(FormatString("%e",tpehis),5,6) ,1)};

992
Richard Stegeman
AIMMSian
R
AIMMS Partner
RichardAIMMS Partner
asked in AIMMS Language
How many rows to read from an excel file (axll)?

Somehow, we never got this question before. It does indeed sound like a very useful addition to the axll library. I checked the documentation of the third party library that AIMMS is using to implement the axll library and there are indeed functions to retrieve this information. We will add the following functions in one of the upcoming releases of AIMMS:  getLastUsedRow getLastUsedColumn and just to be complete: getFirstUsedRow getFirstUsedColumn (Update: released as of AIMMS 4.70.4!)

4056
Mischa
AIMMSian
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