Newton-Raphson

newton-raphson.py

def func(x):
##  Main function.

    return pow(x, 3) - 7 - 5 * x # Change to suit your needs

def derive(x, y=5):
##  Deriving
    
    if 0 <= y <= 10:
        h = pow(10, -10)
        deriv = (func(x+h) - func(x)) / h
        floatpoints = "%." + str(y) + "f"
        return float(floatpoints % deriv)
    else:
        exit("Error:\n y must be between 0 and 10.");
        
def newtonraphson(x, y=5, debug=False):
##  Implementing the Newton-Raphson method 

    lastnum = x
    currentnum = None
    
    while lastnum != currentnum or currentnum == 0:
        if currentnum != None:
            lastnum = currentnum
        else:
            lastnum = lastnum
        i = lastnum
        currentnum = i - (func(i)/derive(i, y))
        if debug == True:
            print currentnum
    floatpoints = "%." + str(y) + "f"
    return float(floatpoints % currentnum)
    
print(newtonraphson(-50, 3, True))