trig functions for bc

trig.bc

#!/usr/bin/bc -q
#
# PURPOSE: This script calculates sine, cosine and tangent using
# the Taylor series.

scale=6

pi = 3.14159265358979323844

define factorial(a) {
  i = a - 1
  for ( ; i >= 1 ; i-- ) {
   c = a * i
   a = c
  }
  return a
}

define sin(x) {
  a=((x^3)/factorial(3))
  b=((x^5)/factorial(5))
  c=((x^7)/factorial(7))
  d=(((x - a) + b) - c)
  return d
}

define cos(x) {
  a=((x^2)/factorial(2))
  b=((x^4)/factorial(4))
  c=((x^6)/factorial(6))
  d=(((1 - a) + b) - c)
  return d
}

define tan(x) {
  return sin(x)/cos(x)
}

print "\nNumber: " ; x = read ()
print "\n\tsin: " ; sin(x*pi/180)
print "\tcos: " ; cos(x*pi/180)
print "\ttan: " ; tan(x*pi/180)
print "\n"

quit