MATLAB: Error in load.m? “Unexpected Matlab Operator”

ccompilerfilegccloadload.moperatorscriptworkspace error

Dear community,

I'm quite new to Matlab, so please excuse if this is a stupid question:

I'm trying to load a .mat-file I've saved, but no matter whether I double click on it or type load(file), an error occurs:

Error: File: load.m Line: 1 Column: 1 Unexpected MATLAB operator.

load.m seems to be written in some sort of C or so, and maybe the problem then has something to do with the fact that I had to install a new gcc compiler recently (gcc 4.7.4) to be able to create a mex-file to run another script. Before I did that, load.m was working. But I don't know what to do now. Does anyone have a clue? Or am I overlooking something?

Thanks a lot!

Best Answer

Hi,

you might not but it seems that Nicola Pero did some years ago ;-). The location of load.m indicates that it belongs to some testing, but it's not the load that comes with MATLAB.

Second, it's not a MATLAB file at all: although it's name is ".m" it's clearly a C/C++ or ObjC file.

Remove that folder from the MATLAB path (e.g. using pathtool) and it should look much better.

Titus

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MATLAB: Can I create a C++ MEX-file S-function

We officially support C++ MEX-file S-functions as of Simulink 4.0 (R12).

To view an example of how to do this, please type:

sfundemos

at the MATLAB Command Prompt. This will open sfundemos.mdl. This demo that ships with SIMULINK provides examples of how to write different types of S-Functions and includes a C++ example.

You can also take a look at chapter 4 of the "Writing S-function" manual which has a good description on writing C++ MEX-file S-functions.

When writing the S-function, declare the MEX Function as extern "C". The rest of the code that you write can all be in C++. For example:

 extern "C" 
 {
 void mexFunction(
     int nlhs_,
     mxArray *plhs_[],
     int nrhs_,
     const mxArray *prhs_[])
 {
   /* Body can use all C++ language features and file can be compiled with a
      C++ compiler
    */
 }
 }

Below is the 'Timestwo' example written as a C++ file. You can compile the file using the MEX command. Note that if you are using the Watcom compiler, you need to add the -DNO_BUILT_IN_SUPPORT_FOR_BOOL flag to your COMPFLAGS option in your options file.

If you are using MSVC 5.0, you do not need to add this flag. The C compiler will automatically know to compile it as C++ code using the mex command.

 /*
* TIMESTWO An example C-file S-function for multiplying an input by 2
*      
*      y  = 2*x
*   
*   See sfuntmpl.c for a general S-function template.
*
*   See also VSFUNC, DSFUNC, SFUNTMPL.
* 
*   Copyright (c) 1990-96 by MathWorks, Inc.
*   All Rights Reserved
*   $Revision: 1.1 $
*/
 #ifdef __cplusplus
     extern "C" {
 #endif
 #define S_FUNCTION_NAME timestwo_level1_cpp
 /* The following three lines are necessary for the WATCOM compiler
* only. You need to remove these lines for the MSVC compiler.
*/
 #ifndef COMPILER_SUPPORTS_BOOL
 typedef int bool;
 #endif
 #include "simstruc.h"
 /*
* mdlInitializeSizes - initialize the sizes array
*/
 static void mdlInitializeSizes(SimStruct *S)
 {
     ssSetNumContStates(    S, 0);   /* number of continuous states */
     ssSetNumDiscStates(    S, 0);   /* number of discrete states */
     ssSetNumInputs(        S, DYNAMICALLY_SIZED);   /* number of inputs */
     ssSetNumOutputs(       S, DYNAMICALLY_SIZED);   /* number of outputs */
     ssSetDirectFeedThrough(S, 1);   /* direct feedthrough flag */
     ssSetNumSampleTimes(   S, 1);   /* number of sample times */
     ssSetNumSFcnParams(    S, 0);   /* number of input arguments */
     ssSetNumRWork(         S, 0);   /* number of real work vector elements */
     ssSetNumIWork(         S, 0);   /* number of integer work vector elements */
     ssSetNumPWork(         S, 0);   /* number of pointer work vector elements */
 }
 /*
* mdlInitializeSampleTimes - initialize the sample times array
*/
 static void mdlInitializeSampleTimes(SimStruct *S)
 {
     ssSetSampleTime(S, 0, CONTINUOUS_SAMPLE_TIME);
     ssSetOffsetTime(S, 0, 0.0);
 }
 /*
* mdlInitializeConditions - initialize the states
*/
 static void mdlInitializeConditions(double *x0, SimStruct *S)
 {
 }
 /*
* mdlOutputs - compute the outputs
*/
 static void mdlOutputs(double *y, double *x, double *u, SimStruct *S, int tid)
 {
     class mul2 {
         double            *u;
         double            *y;
         int                width;
     public:
         mul2(double *u_i, double *y_i, int width_i) 
         {
             u = u_i;
             y = y_i;
             width = width_i;
         }
         void output(void) 
         {
             for (int i=0;i<width;i++)
             { 
                 *y++=2.0*(*u++); 
             }
         }
     };
     class mul2 m(u,y,ssGetNumOutputs(S));
     m.output();
 }
 /*
* mdlUpdate - perform action at major integration time step
*/
 static void mdlUpdate(double *x, double *u, SimStruct *S, int tid)
 {
 }
 /*
* mdlDerivatives - compute the derivatives
*/
 static void mdlDerivatives(double *dx, double *x, 
                            double *u, SimStruct *S, int tid)
 {
 }
 /*
* mdlTerminate - called when the simulation is terminated.
*/
 static void mdlTerminate(SimStruct *S)
 {
 }
 #ifdefMATLAB_MEX_FILE    /* Is this file being compiled as a MEX-file? */
 #include "simulink.c"      /* MEX-file interface mechanism */
 #else
 #include "cg_sfun.h"       /* Code generation registration function */
 #endif
 #ifdef __cplusplus
     }
 #endif

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