strnums

Matlab code to pull numbers out of strings

strnums is a function to scan through a string and isolate just the
numbers before converting to a number.
Optional handling choices are as follows
1. Concatenate all numeric characters together to convert to a
single number, disregarding any separating characters. Leading
zeros are lost except where only zeros exist.
2. Concatenate only adjacent numeric characters, returning a
number per separate block. Leading zeros in any block are lost
except where only zeros exist
3. Concatenate adjacent numeric characters, ignoring undefined
separator characters, but grouping characters according
the characters listed in inputs
4. Return each digit separately