Coder and passing extra parameters

Hi all,

I have been trying to speed up the passing of extra parameters to a function that is used in fzero(). I have been trying to create code that is compatible with and can be compiled by the coder. Since nested functions and function handles aren't compatible I have been trying to get the following code compiled.

    function z = RxEqNest2(z1,pin2,pin3,pT,pVpore)%#codegen
  global in2 in3 T Vpore
  in2=pin2;
  in3=pin3;
  T=pT;
  Vpore=pVpore;

z = fzero(@RxEqPoly2,z1);
end

function out1 = RxEqPoly2(z)
global in2 in3 T Vpore
%RXEQPOLY2
%    OUT1 = RXEQPOLY2(Z1,IN2,IN3,T,VPORE)

%    This function was generated by the Symbolic Math Toolbox version 5.7.
%    15-Sep-2011 22:07:14

Keq1 = in2(:,1);
Keq2 = in2(:,2);
Keq3 = in2(:,3);
Ot = in3(:,2);
t107 = z.^2;
out1 = T.*t107.*(5.774280410608897e15./1.7592186044416e13)+Ot.^2.*T.*(5.774280410608897e15./7.0368744177664e13)+Keq2.*T.*t107.*(5.774280410608897e15./8.796093022208e12)-Ot.*T.*z.*(5.774280410608897e15./1.7592186044416e13)+Keq2.^2.*T.*t107.*(5.774280410608897e15./1.7592186044416e13)-Keq1.^2.*Vpore.*z-Keq3.^2.*Vpore.*z-Keq1.*Keq3.*Vpore.*z.*2.0-Keq2.*Ot.*T.*z.*(5.774280410608897e15./1.7592186044416e13);
end

I get errors during the compilation of the subfunction, saying that it can not find size declarations of in2,in3,T. How can passing parameters efficiently be done when this step is a major bottleneck compared the time spent evaluating the function.

Thanks

[Joseph]

Error message:

Could not find initial value for global variable 'in2'.

Answer 1

[Alexander Bottema]

Hello Joseph,

Could you show us the 'codegen' command you're using to compile your code with? You need to use '-globals' to specify initial values for the global variables (even though these values will not be used). The initial values are used to determine the class/size/complexness of the global variables.

Thanks, Alexander

[Joseph]

I didn't realize to do that because the variables were declared and wanted to limit the scope of them to the mex function, but thanks for the clarification. I tend to minimize my use of globals but didnt know another way to pass extra parameters and still be compatible with the coder. I used this:

codegen RxEqNest2 -args {1,Keq{1},Elements_eg,T_eg,Vpore_eg} -globals {'in2',Keq{1},'in3',Elements_eg,'T',T_eg,'Vpore',Vpore_eg}