#!/usr/local/bin/python
# Function to calculate Board foot volume 
# from small end diameter and log length
# by David R. Larsen, October 11, 2012
# Creative Commons,  http://creativecommons.org/licenses/by-nc/3.0/us/

# Function to calculate Doyle Board foot volume 
# from small end diameter and log length
def doyle( sdia, length):
    value = (( sdia - 4.0) / 4.0 )**2 * length
    return value

# Function to calculate the Scribner Board foot volume 
# from small end diameter and log length
def scribner( sdia, length):
    value = ( 0.79 * sdia**2 - 2 * sdia - 4 ) * (length / 16)
    return value

# Function to calculate the International Board foot volume 
# from small end diameter and log length
def intVolume( sdia, length):
    if( length == 4 ):
      value = 0.22 * sdia**2 - 0.71 * sdia
    elif( length == 8 ):
      value = 0.44 * sdia**2 - 1.20 * sdia - 0.30
    elif( length == 12 ):
      value = 0.66 * sdia**2 - 1.47 * sdia - 0.79
    elif( length == 16 ):
      value = 0.88 * sdia**2 - 1.52 * sdia - 1.36
    elif( length == 20 ):
      value = 1.10 * sdia**2 - 1.35 * sdia - 1.90
    elif( length == 24 ):
      value = 1.10 * sdia**2 - 1.35 * sdia - 1.90 + 0.22 * sdia**2 - 0.71 * sdia
    elif( length == 28 ):
      value = 1.10 * sdia**2 - 1.35 * sdia - 1.90 + 0.44 * sdia**2 - 1.20 * sdia - 0.30
    elif( length == 32 ):
      value = 1.10 * sdia**2 - 1.35 * sdia - 1.90 + 0.66 * sdia**2 - 1.47 * sdia - 0.79
    elif( length == 36 ):
      value = 1.10 * sdia**2 - 1.35 * sdia - 1.90 + 0.88 * sdia**2 - 1.52 * sdia - 1.36
    elif( length == 40 ):
      value = (1.10 * sdia**2 - 1.35 * sdia - 1.90) * 2 
    return value


# test of functions

print( "doyle =", doyle(sdia=10,length=16))
print( "doyle =", doyle(sdia=28,length=16))
print( "scribner =", scribner(sdia=10,length=16))
print( "scribner =", scribner(sdia=28,length=16))
print( "International volume =", intVolume(sdia=10,length=16))
print( "International volume =", intVolume(sdia=28,length=16))