Function 'subsindex' is not defined for values of class 'struct'.

Dear All This is a part of my code

if gurobi
  clear prob
  prob.obj=full(obj);
  prob.A=equalityMatrix;
  prob.rhs=full(equalityRHS);
  prob.sense=['='];
  prob.lb=full(lowerB);
  prob.up=full(upperB);
  params.Method=2;
  params.Crossover=0;
  params.outputflag = 0;
  res = gurobi(prob, params);
  if ~strcmp(res.status,'OPTIMAL')
      disp(res.status);
  end
  solution=res.objval;
  variables=res.x;

When I am running it I get this error: Function 'subsindex' is not defined for values of class 'struct'.

could you please inform me how to fix this problem

[Matt J]

Copy/paste the full error message.

[Bestun]

Dear Math this is the whole error message

Function 'subsindex' is not defined for values of class 'struct'.

[Matt J]

No, it can't be the whole thing. For example, the code below results in the error message

Error using subsindex
Function 'subsindex' is not defined for values of class 'struct'.

Error in test (line 10)
  gurobi(prob,params);

Notice that it includes a line number and the specific statement that triggered the error.

    gurobi=1;

      params.Method=2;
      params.Crossover=0;
      params.outputflag = 0;

      prob=params;

      gurobi(prob,params);

[Eric Sirott]

nope, I've had the same problem and I too was perplexed when there wasn't a line number.

Answer 1

[Walter Roberson]

Your first line,

if gurobi

implies that gurobi is more likely a variable than a function. But later you have the line

res = gurobi(prob, params);

where prob and params are struct. If gurobi is a variable there, then you are trying to use the struct as indices, which MATLAB would give an error message for (the one you are seeing.)

In order for gurobi to be a function, then for it to be consistent with "if gurobi", then it would be necessary for it to be possible to invoke gurobi with no parameters (instead of with two parameters). That is possible, but if that is your intent then it would be clearer for readers if you were to write

if gurobi()

[Bestun]

Dear Walter Thanks for you answer Gurobi is a solver could be used in Matlab. What did you say seems reasonable, but I am still getting the same problem

[Walter Roberson]

At the MATLAB command line, enter the command

dbstop if error

then run your program. When it stops, show us which line it stopped on, and also please show us the result of

which -all gurobi

and

whos gurobi