bisec.py

from math import cos
from math import sin as sen
from math import tan
from math import e

def bisec(fx, a, b, iteraciones):
    for i in range(iteraciones):
        print "----------------------------------"
        x = a
        fa = eval(fx)

        x = b
        fb = eval(fx)

        m = ((a+b)/2.0)

        x = m
        fm = eval(fx)

        print "a= %s fa= %s" %(a, fa)
        print "b= %s fb= %s" %(b, fb)
        print "fm= %s" %(fm)
        print "m%s = (%s - %s) / 2 = %s" %(i+1, a, b, m)

        if fm < 0:
            if fa>0:
                # [a, m]
                b = m
            else:
                # [m, b]
                a = m
        else:
            if fa<0:
                # [a, m]
                b = m
            else:
                # [m, b]
                a = m


funciones = [
    ["(x**3)-x-1", 1, 2],
    ["(x**4)+(x**2)-4", 1, 2],
    ["(x**3)+(2*x)+8", -2, -1],
    ["(2*(x**2))+(cos(x))-x-2", 0, 3],
    ["((x**2)/(cos(x)))-x-10", -1.5, 0],
    ["(sen(x))/((x**2)+1)", -4, -2],
    ["((tan(x))/x+1)-(2*x)-1", 0.1, 1],
    ["(e**((x**2)+1))-5", -1, 0],
    ["cos((x**2)+1)", 2, 3],
    ["(2*(x**3))-(sen((x**2)+1))", 0, 1]
]

c = 1

for f in funciones:
    fx = f[0]
    a  = f[1]
    b  = f[2]

    print "\n##################################"
    print "%s) f(x) = %s from %s to %s" %(c, fx, a, b)
    bisec(f[0], f[1], f[2], 5)

    c += 1