str2doublef

Fast approximate string to double parsing for real or complex numbers.

Fast approximate string to double or complex parsing for %f and %e formatted numbers such as '25.423', '0.0069', '+1.2', '-124.67', '2.0e-10', '6.02214076e23', and '23 + -5i', 'i', 0 + -i', '-25e+5 + -5e-2i', '10i', '5i-2', '2 +76i', etc. For complex numbers the relevant numeric substrings may appear in either a real then imaginary or imaginary then real order. Parsing is performed from right to left and issues related to overflow, underflow, and potential loss of precision are ignored. The intent is to provide a fast and relatively accurate means of parsing formatted real or complex numbers in a %f or %e format, represented as strings of characters, for a broad range of values, but not an attempt to get the maximum precision for the machine representation of a double precision numeric value from a string.