#!/usr/bin/bc -l
#
# Compute the allowed sending rate X_calc using the formula of [RFC 3448, 3.1].
#
# This script can be run standalone, or using a pipe.
# For example, to compute  for 
#   *   s=1424  bytes, 
#   * RTT= 150  milliseconds, and 
#   *  p =  10  %,
# use
#	 echo 1424 150 10 | ./throughput_calculator.bc
#
# The result is about 132 Kbits/sec

scale = 3

define f(p) { return sqrt(2*p/3) + 12 * sqrt(3*p/8) * (32 * p^3 + p) }
define xcalc(s,r,p) { return s*8 * 10^3/(r * f(p/100.0)) }

print "TFRC throughput calculator\n\n"

print "s   in bytes: "; s = read()
print "RTT in msecs: "; r = read()
print "p   in %    : "; p = read()

print "\nXcalc = ", xcalc(s,r,p) / 1024.0, " Kbits/sec\n"
quit