What are the valid formats for numbers in MATLAB? - matlab

Question

What are the valid formats are for numbers in MATLAB? The following seem to be valid:
x=0;
x=0.;
x=0.0;
x=0e0;
x=0E0;
x=0000.00; % Trailing and leading zeros seem to be irrelevant
Are there other valid general number specifications? I can't find this in the documentation.

Answer 1

I believe this is the regex of floating-point number formats, valid in MATLAB:
^[-+]*([0-9]+|[0-9]*\.[0-9]+|[0-9]+\.[0-9]*)([eEdD][+-]?[0-9]+)?$
Compiled from here, and slightly modified for MATLAB:
added 'd' exponent character (as is common in FORTRAN, MATLAB's ancestor)
added uppercase exponent characters
added extra case in the required order before and after the decimal symbol
I'm pretty sure the locale can mess this up, e.g., the decimal separator . might be set to , as is common here in Europe. Oh well.
The regex in words:
string start, followed by
zero or more consecutive sign symbols, followed by
non-zero length string of consecutive integers, OR
possibly zero-length string of consecutive integers, followed by a dot, followed by non-zero length string of consecutive integers, OR
non-zero length string of consecutive integers, followed by a dot, followed by a possibly zero-length string of consecutive integers
optionally followed by the exponent part:
one of e, E, d or D.
zero or one sign symbols, followed by
non-zero length string of consecutive integers
followed by string terminator
Note that this is for non-complex floating point values. For complex values, you'd have to
use the regex once for the real, once for the imaginary part
append [ij]{1} to the imaginary part (only lower case)
take care of spacing (\s*) and a [+-]{1} in between the two parts
take care of the fact that the imaginary part may appear alone, but the real part may not appear with a trailing [+-]{1}, but no imaginary part.