regexprep
regexprep(str,ex,repstr) returns string str for which occurrences of regular expression ex have been replaced with repstr.
Examples
>> regexprep('bcd', '^', 'a')#% add 'a' at the beginning of a line
abcd
>> regexprep('bcd', '^', 'a')#% add 'a' at the beginning of a line
abcd