1 a/b - HW2

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

#Determinar a Inversa de A
import numpy as np
import pylab as pl



epsilon = 0.1

A = 0.5* np.array([1+epsilon, 1-epsilon, 1, 1]).reshape(2,2) #matriz esta definida

def isSquare (m): return all (len (row) == len (m) for row in m)

def determinante(a):
    if not isSquare(a):
        return False
    return a[0,0]*a[1,1] - a[1,0]*a[0,1]


def inversa(a):
    det = determinante(a)
    inv = np.array( [a[1,1],-1*a[0,1],-1*a[1,0],a[0,0] ]).reshape(2,2)
    return 1./det * inv

def modulo(a): #Modulo de Frobenius
    return np.sqrt(np.sum(a*a))


def cond(a):
    mod1 = modulo(inversa(a))
    mod2 = modulo(a)
    return mod1 * mod2



# Parte do MAIN
print 'Inversa'
print inversa(A)


set_e = np.linspace(0.001, 0.1, 300)

c_nr = np.zeros(np.size(set_e))

for l in np.arange(np.size(c_nr)):
    epsilon = set_e[l]
    A = 0.5* np.array([1+epsilon, 1-epsilon, 1, 1]).reshape(2,2)
    c_nr[l] = cond(A)

pl.figure()

pl.plot(set_e, c_nr)

pl.show()