Converting output results to 00e+00 form

I have this:

 iL=vpa(dsolve(eqn1,inits,'t'),4)
iL =
0.00467 - 0.0002202*exp(-133.2*t)*sin(2825.0*t) - 0.00467*exp(-133.2*t)*cos(2825.0*t)

How can I get the results like

iL = 4.67e-3 - 2.202e-4*exp(-1.332e+2t)*....

Thanks

Answer 1

[Jonathan Epperl]

So that you can change the output format by issuing

 format STYLE

in your case

 format shortE

you probably knew. And it won't help you here. The only idea I have is converting to string and doing some regular expression magic. So if iL is your symbolic expression. Then this command will get you a string res_str that contains the symbolic expression with all numbers (with decimals) converted to scientific notation

 iL = 0.00467 - 0.0002202*exp(-133.2*t)*sin(2825.0*t)-.00467*exp(-133.2*t)*cos(2825.0*t)

 res_str = regexprep(char(vpa(iL)),'([0-9]+\.[0-9]+)','${num2str(str2num($1),''%e'')}')

%res_str =

    %4.670000e-03 - 2.202000e-04*exp(-1.332000e+02*t)*sin(2.825000e+03*t)-
    %4.670000e-03*exp(-1.332000e+02*t)*cos(2.825000e+03*t)

(The extra vpa() command in regexprep is obviously unnecessary here if you called it on your expression earlier already)

Now if you reconvert to a sym, the numbers will be represented in the normal decimal format again, but that shouldn't be a problem: If you want to do algebra with it, use the sym variable, if you want to display use the string form.

[Shahram]

Thanks for your answer, this is a good solution, but I'm looking to get the Matlab to produce these results without playing with characters.

[Jonathan Epperl]

I don't think there's a way, but if you find one, let us know!

Answer 2

[Walter Roberson]

When you are going through the MATLAB interface, the only options you have for representation in MuPAD are those shown under "flag" in the documentation for "sym".

I do not have the symbolic toolbox to check against; it could be that by working more directly in MuPAD you could force an exponential notation.