fixed point iteration issue [closed]

edit

Im having a problem with this code wonder if someone could help me, its a code for fixed point iteration:

def valores(f,p,a,b,xi,n):
    var('k,xk,fi,ErAbs,ErRel,ErMet')
    a==a
    b==b
    xi==xi
    x1=p(xi)
    L=[[k,xk,fi,ErAbs,ErRel,ErMet]]
    for i in range (0,n):
        L.append([n,xi,x1,er,ea,em])
        er = abs(x1-xi)
        if xi > 1:
            ea = er/xi
        else:
            ea = er
        em = ea*(l*(1-l))
        xi=p(xi)
        x1 = p(xi)
    return (matrix(L))

@interact
def Exp(n = selector(range(0, 11),nrows=1, label="Botão"),f = input_box(default=x*e^x-1), a = input_box(default=0.5), b = input_box(default=1), xi = input_box(default=0.8),p = input_box(default=e^(-x)):
    df = diff(f,x)
    dp = diff(p,x)
    if df(x) > 0:
        l = abs(dp(b))
    else:
        l = abs(dp(a))
    show(valores(f,p,a,b,xi,n))

Error showed:

Traceback (most recent call last): File "<stdin>", line 1, in <module> File "_sage_input_117.py", line 10, in <module> exec compile(u'open("___code___.py","w").write("# -*- coding: utf-8 -*-\\n" + _support_.preparse_worksheet_cell(base64.b64decode("QGludGVyYWN0CmRlZiBF\ eHAobiA9IHNlbGVjdG9yKHJhbmdlKDAsIDExKSxucm93cz0xLCBsYWJlbD0iQm90w6NvIiks\ ZiA9IGlucHV0X2JveChkZWZhdWx0PXgqZV54LTEpLCBhID0gaW5wdXRfYm94KGRlZmF1bHQ9\ MC41KSwgYiA9IGlucHV0X2JveChkZWZhdWx0PTEpLCB4aSA9IGlucHV0X2JveChkZWZhdWx0\ PTAuOCkscCA9IGlucHV0X2JveChkZWZhdWx0PWVeKC14KSk6CiAgICBkZiA9IGRpZmYoZix4\ KQogICAgCiAgICBkcCA9IGRpZmYocCx4KQogICAgCiAgICBpZiBkZih4KSA+IDA6CiAgICAg\ ICAgbCA9IGFicyhkcChiKSkKICAgIGVsc2U6CiAgICAgICAgbCA9IGFicyhkcChhKSkKICAg\ ICAgICAKICAgIHNob3codmFsb3JlcyhmLHAsYSxiLHhpLG4pKQ=="),globals())+"\\n")\ ; execfile(os.path.abspath("___code___.py"))' + '\n', '', 'single') File "", line 1, in <module> File "/tmp/tmpWfUq28/___code___.py", line 4 def Exp(n = selector(range(_sage_const_0 , _sage_const_11 ),nrows=_sage_const_1 , label="Botão"),f = input_box(default=x*e**x-_sage_const_1 ), a = input_box(default=_sage_const_0p5 ), b = input_box(default=_sage_const_1 ), xi = input_box(default=_sage_const_0p8 ),p = input_box(default=e**(-x)): ^ SyntaxError: invalid syntax