I use Save and Get routinely in Mathematica. How can I get saved variables and functions from Mathematica into Matlab?

I use Save and Get routinely in Mathematica. How can I get saved variables and functions from Mathematica into Matlab?

[Geoff Hayes]

Wayne - do you mean that you have functions that you have written in Mathematica that you wish to use (import) into MATLAB? And that you have data (files) that have been saved in Mathematica that you wish to import into MATLAB too?

[Wayne McKinney]

I have done several large symbolic calculations that output MacLaurin series. Mathematica Saves a file with coefficients in the series as square bracket functions like coefficien[2,0]= long polynomial expression. My customer does not use Mathematica, only Matlab. He wishes to plug numbers into the polynomials, and make plots.

[dpb]

Attach a sample of one of the files...

[Wayne McKinney]

Done

[Walter Roberson]

Mathematica has an export to matlab facility.

[Wayne McKinney]

Yeah, from 1999. I have been trying all day to get it to work.

Answer 1

[Walter Roberson]

file_in = 'diaboloid_aij.txt';
file_out = 'diaboloid_aij.m';
S = fileread(file_in);
Snew = regexprep(S, {'\[(\d+),', '(\d+)\]', '\[', '\]', 'Cos', 'Sin', 'Tan', 'Sec', '([-+*/])\s*$', '\)\s*$'}, {'(1+$1,', '1+$1)', '(', ')', 'cos', 'sin', 'tan', 'sec', '$1 ...', ');'}, 'lineanchors');

fid = fopen(file_out, 'w');

fwrite(fid, Snew);
fclose(fid);

clear diaboloid_aij  %flush any saved versions of the file

Script diaboloid_aij is now ready to run after you have defined numeric values or symbolic names for the variables.

[Wayne McKinney]

Thank you! I am bushed after chasing this all day. I will try your solution tomorrow. I have been doing Mathematica since the beginning, but not being a MatLab maven, I cannot tell just looking at it. I suspect your have nailed it though. I did get Mathematica to write something I could read in Matlab--a text file. :)

[Walter Roberson]

Example output:

     coefmatrix(1+0, 1+2) = ((rp + rs)*sec(a))/(4*rp*rs);
     coefmatrix(1+0, 1+4) = ((rp + rs)*(5*rp + rs + (3*rp - rs)*cos(2*a))*sec(a)^3)/ ...
          (128*rp^3*rs^2);
     coefmatrix(1+0, 1+6) = (sec(a)*(-2*rp^4 + 7*rp^3*rs + 5*rp^2*rs^2 - 3*rp*rs^3 + ...
            rs^4 + 2*(rp + rs)^2*(rp^2 + 2*rp*rs - rs^2)*sec(a)^2 + ...
            rs*(rp + rs)^3*sec(a)^4))/(512*rp^5*rs^4);

The code is not perfect: in some cases it could miss out adding a semi-colon at the end of an expression. In every expression that happened to be in your file, the expression ended with a ')' and I rely on that to kick on the semi-colon.

[Wayne McKinney]

Seems to work beautifully! I had to add ... after = on lines 108 and 152.

[Walter Roberson]

Ah. The code I was working with originally would have taken care of that, but unfortunately I had some difficulty in getting it to match in "something that is not ) followed by any amount of whitespace followed by end of line"