4H2012 area.py

#!/usr/bin/python
from matplotlib import *
from pylab import *

o=input("o=? (0:left,0.5:mid,1:right)")
a=input("a=?")
b=input("b=?")
n=input("n=?")
f=raw_input("f(x)=?")

def findArea(o,a,b,n,f):
    h=1.0*(b-a)/n
    x=[a+(i+o)*h for i in range(n)]
    y=[f(a+(i+o)*h) for i in range(n)]
    areas=[f(a+(i+o)*h)*h for i in range(n)]
    area=sum(areas)
    return area

def drawArea(o,a,b,n,f):
    h=1.0*(b-a)/n
    x=[a+(i+o)*h for i in range(n)]
    y=[f(a+(i+o)*h) for i in range(n)]
    plot(x,y,color='red')
    for i in range(n):
        matplotlib.pyplot.gca().add_patch(matplotlib.patches.Rectangle((a+i*h,0),h,f(a+(i+o)*h)))
    show()

print "area=",findArea(o,a,b,n,lambda x:eval(f))
drawArea(o,a,b,n,lambda x:eval(f))