[Scip] How can I read the values of fixed variables in the collected feasible solutions

[Gerald Gamrath]

Dear Sheetal,

you can find all methods that access the variable data structure 
directly in pub_var.h:
http://scip.zib.de/doc/html/pub__var_8h.shtml
There, you can also find the methods mentioned by Michael, which are the 
correct way to get the value of a fixed variable.

You can find public methods of SCIP either in pub_xyz.h for things that 
deal with structure xyz, e.g. var, cons, sol,...
Methods that need more data, e.g. the problem (for transferring solution 
values), settings, and a solution can be found in scip.h.
Additionally, all methods for a specific plugin, e.g. cons_linear can be 
found in the corresponding .h-file.
Thus, if you are searching for a specific method, there are just two 
places to look: the corresponding pub_xyz.h file and scip.h (which is 
also devided into sections concerning different topics).

However, back to your primary question, if you just want to get the 
solution with respect to the original variables, you can also do the 
following:
1) Get the original variables and their number by calling 
SCIPgetOrigvarsData():
     
http://scip.zib.de/doc/html/scip_8h.shtml#a26493edb8b80908a3c46ed8d66e335e9
     (alternatively, you can also use SCIPgetOrigVars() and 
SCIPgetNOrigvars():
     
http://scip.zib.de/doc/html/scip_8h.shtml#abec020b8686cac2812d1028deece85f9) 
and
     
http://scip.zib.de/doc/html/scip_8h.shtml#aac6e0dce5ed1e58242b015a469b7ce16)
2) Get the solution values of these variables via SCIPgetSolVal() or 
SCIPgetSolVals(), which gives you all values in one call:
     
http://scip.zib.de/doc/html/scip_8h.shtml#adbd8d051e9c1b3f2d84be42fb140c112
     
http://scip.zib.de/doc/html/scip_8h.shtml#a982669e32c6756f863a1cc3741ecf32c

SCIP will automatically compute the value of an original variable when 
asked for its value in a transformed solution. That means that it 
handles fixed variables, but also (multi-)aggregated variables, which 
you would also have to do if you want to do everything by hand.

Best,
Gerald

Am 12.08.2012 10:11, schrieb michael.winkler at zib.de:
> Hi,
>
> you need to loop over all fixedvars and ask for
> SCIPvarGetLbGlobal(fixedvars[..]) (or SCIPvarGetUbGlobal(fixedvars[..])).
> For fixed variables the global lowerbound and upperbound should be the same.
>
> Best, Michael
>
>> Hello,
>>
>> I want to obtain the values of all the variables in the collected feasible
>> solutions in SCIP.
>> I could collect the feasible solutions and could transform those variable
>> to the original variable space.
>>
>> I want to obtain the values of the fixed variables.
>> I have used the following methods for getting number and SCIP_VAR**
>> structure array of the fixed variables.
>>
>> SCIP_VAR** fixedvars;
>> fixnum  = SCIPgetNFixedVars(scip);
>> fixedvars = SCIPgetFixedVars(scip);
>>
>> Could you please let me know how I can read the values of the fixed
>> variables in the collected feasible solutions.
>> How can I read the values of structure elements for SCIP_VAR**?
>>
>> --
>> Thanks with Best Regards,
>> Sheetal
>>
>> :)
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