This is a question of *how* does it ksh *right* where other tools (awk) fail.
The task was to get the number of digits in a decimal number. (N.B.: the log()
division was used instead of log10() because of the latter's unavailability in
awk.)
$ awk 'BEGIN {print (log(999)/log(10))+1}'
3.99957
$ awk 'BEGIN {print (log(1000)/log(10))+1}'
4
Adding an int() call to above functions:
$ awk 'BEGIN {print int(log(999)/log(10))+1}'
3
$ awk 'BEGIN {print int(log(1000)/log(10))+1}'
3
The last result is wrong (due to internal rounding/accuracy problems in FP
arithmetics [see Goldberg's paper on FP arithmetics]).
Contrary to awk, ksh correctly does (without and with the int() call):
$ echo $(( log(1000)/log(10)+1 ))
4
$ echo $(( int(log(1000)/log(10))+1 ))
4
I'm assuming that both tools, awk and ksh, use C library functions for FP
arithmetic. - What does ksh internally do to create a correct result?
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