Error writing to a file

I have a gamainfile

options = optimoptions('gamultiobj','UseParallel', true,'UseVectorized', false,'ParetoFraction',0.35,...

'PopulationSize',60,'Generations',60, 'CrossoverFraction',0.5,'CrossoverFcn',@crossoverintermediate ,'MutationFcn',...

@mutationadaptfeasible)

[X,fval,exitflag,output,final_pop]=gamultiobj(@functionfile,NumVar,A,b,[],[],...

Xlow,Xup,options);

The function file has

Input parameters X(1)…X(6), constants

[time1,Y1]=ode15s(odefn1…..)

[time2,Y2]=ode15s(odefn1…..)

Y1 and Y2 have dimensions (n x 270)

n is the number of rows based on the time step

Calc1 to Calc4 are calculated by integrating various Y values in Y1 and Y2.

calc1= f1(Y1,Y2);

calc2= f2(Y1,Y2);

calc3= f3(Y1,Y2);

calc4= f1(Y1,Y3);

The objectives are

Obj1 =Calc3/100+ 10000*(max(0,constraint1-calc1/100))^2+10000*(max(0,constraint2-calc3/100))^2;

Obj2 =1/calc4+ 10000*(max(0,constraint1-calc1/100))^2+10000*(max(0,constraint2-calc3/100))^2;

filename = [tempname('directory name),'.txt'];

fid = fopen(filename,'w');

fprintf(fid, '%f %f %f %f %f %f %f %f %f %f\n',X(1),X(2),X(3),X(4),X(5),X(6),calc1,calc2,calc3,calc4);

fclose(fid);

I get an error message

Invalid fileID for worker. File operations must occur on the worker where the file was opened

How do I avoid this error and is there a better way to save all the values that I write to the files..

Answer 1

[Ganapathi Subramanian]

It is my understanding that you are working on a program to store its data inside a file and have trouble in writing the data to the file. Refer to the below code snippet for writing the data to a unique temporary file.

filename=[tempname('C:/foldername'),'.txt']; 
fid=fopen(filename,'w'); 
i=5.6; 
fprintf(fid,'%f',i); 

For more information regarding ‘tempname’, refer this link

https://www.mathworks.com/help/matlab/ref/tempname.html

Refer to the below documentation for more information regarding ‘fprintf’.

https://www.mathworks.com/help/matlab/ref/fprintf.html

[Shreenath Krishnamurthy]

Hi Ganapathi subramaniam. Perhaps my question was not clear.

I know how to write to a text file and basically your snippet is the same as mine.

What i dont understand is why i get an invalid file id. A temp file name is supposed to have an unique name and even if multiple files access the same work it should not be a problem right ? If it is a problem then what is the solution

[Ganapathi Subramanian]

Hi Shreenath Krishnamurthy,can you please share more information regarding 'if multiple files access the same work it should not be a problem right' .It is not clear.What does 'multiple files' depict? Is it the set of programs?

[Shreenath Krishnamurthy]

Multiple files depict multiple text files. These files have temporary names and write outputs to the input conditions to the ga file. The gamultiobj uses the parallel evaluation option.