int2str takes a scalar argument, and converts it to a string.
It is intended that the argument be integer - if it has any fractional
part, this will be rounded off.
This is not an built-in function. This function
is normally loaded on start-up from the int2str.r file in the
standard rlib directory. Use of the -r option, incorrectly
setting the RLAB_LIB_DIR environmental variable, or modifying
int2str.r may make this function unavailable.