Error using Legacy code: Cannot find a valid lhs expression in the function specification?

** Error using legacycode.LCT.legacyCodeImpl
> legacy_code('sfcn_cmex_generate', def);

after I use the command to generate sfunction i get the above error:*

Source File:

#include "Controller.h"
double Cout, X;
double controller(double Pout, double Pin)
{
  if(Pout>0)
    Cout = -X/2;
  else 
    Cout = X/2;
  return Cout;
}

Header File:

#ifndef _CONTROLLER_H_
#define _CONTROLLER_H_

double contr(double Pout); 

#endif

| *

def.SourceFiles = {'Controller.c'};
  def.HeaderFiles = {'Controller.h'};
  def.SFunctionName = 'ex_sfun_controller';
  def.OutputFcnSpec = 'double y = controller(double u1,double u2)';
  legacy_code('sfcn_cmex_generate', def);*|

How to resolve this error?

[Jan]

Did you notice, that your code is not readable? Please consider http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup .

[Gaurav Agarwal]

You can have a look now

[Walter Roberson]

the function signature in your h file only has one argument but the function signature in your definition has two parameters .

Answer 1

[Aman Kalia]

Hey Gaurav,

I was running into the same issue and found the error I was making. In your def.OutputFcnSpec you need to make sure that output and input variables are represented correctly. In your case, replace def.OutputFcnSpec in your code with the following:

def.OutputFcnSpec = 'double y1 = controller(double u1,double u2)';

Basically change y to y1 and it should work. For passing parameters use p1, p2 , p3 and so on.

Hope this helps.