solve_cylinder_rt.py

#!/opt/miniconda3/bin/python
import numpy as np
from scipy.optimize import fsolve
import sys

def parapiped(w,h,L):
  A=2*(w*h+w*L+h*L)
  V=w*h*L
  return np.array([A,V])
def cylinder(r,t):
  A=2*np.pi*r*(r+t)
  V=np.pi*r**2*t
  return np.array([A,V])

def matchAV(dim_cyl,dims):
  r,t=dim_cyl
  w,h,L=dims
  AVp=parapiped(w,h,L)
  AVc=cylinder(r,t)
  return AVp-AVc

def solve_cylinder(w,h,L):
  r,t=fsolve(matchAV,[1,2],args=[w,h,L])
  print('A %1.2f x %1.2f x %1.2f parallelipiped'%(w,h,L) )
  print('has the same surface area and volume as a cylinder')
  print('that is r=%1.4f and t=%1.4f'%(r,t))
  

if __name__=='__main__':
  if len(sys.argv)<=3:
    print('error, please enter w-by-t-by-L dimensions of parallelipiped as w t L')
  else:
    print(sys.argv)
    w=float(sys.argv[1])
    h=float(sys.argv[2])
    L=float(sys.argv[3])
    r,t=fsolve(matchAV,[1,2],args=[w,h,L])
    print('A %1.2f x %1.2f x %1.2f parallelipiped'%(w,h,L) )
    print('has the same surface area and volume as a cylinder')
    print('that is r=%1.4f and t=%1.4f'%(r,t))