# -*- coding: utf-8 -*-


def traps(a,b,n,f):
    h = (1.*b-a)/n
    s = (f(a) + f(b))*0.5
    
    for i in range(1,n):
        s += f(a + h*i)
    
    return h*s

def traps_p(a,b,n,f):
    t= f(linspace(a,b,num=n+1))
    t[0] = t[0]*0.5
    t[-1] = t[-1]*0.5
    return sum(t)*(1.*b-a)/n


#for ? test funksjonene, format traps.py a b n 'f(x)'     
if __name__ == '__main__':
    import sys
    from numpy import *  #for ? kunne bruke eval
    
    if len(sys.argv) != 5:
        sys.stderr.write("wrong number of args\n")
        sys.exit(2)
        
    print '%f' %(traps(float(sys.argv[1]), float(sys.argv[2]),\
                          int(sys.argv[3]),lambda x: eval(sys.argv[4])))
    print '%f' %(traps_p(float(sys.argv[1]), float(sys.argv[2]),\
                          int(sys.argv[3]),lambda x: eval(sys.argv[4])))