Question

could anyone solve the newtons method prob in week 3 pset??
if yes could u pls gimme the code?

Answer 1

ye i did (and many others) but i wont give you the code-.-....if you want i could help you with your code though!

Answer 2

def computeRoot(poly,x_0,epsilon):
f = evaluatePoly(poly,x_0)
fd=computeDeriv(poly,x_0)
count = 0
while float(fd)!=0:
dx = f / float(fd)
if abs(dx) < epsilon * (1 + abs(x_0)): return int(count)
x_0 = x_0 - dx
f = evaluatePoly(poly,x_0)
fd=computeDeriv(poly,x_0)
count = count + 1

Answer 3

i tried this code i feel its wrong il giv u the prev code temme wats wrong

Answer 4

def evaluatePoly(poly, x):
'''
Computes the value of a polynomial function at given value x. Returns that
value as a float.

poly: list of numbers, length > 0
x: number
returns: float
'''
l=len(poly)
i=l-1
c=0
s=0.0
b=0.0
while c<l:
b=poly[i]*(x**i)
s=s+b
c=c+1
i=i-1
return s

>>> def computeDeriv(poly,x):
'''
Computes and returns the derivative of a polynomial function as a list of
floats. If the derivative is 0, returns [0.0].

poly: list of numbers, length &gt; 0
returns: list of numbers (floats)
'''
l=len(poly)
i=l-1
c=0
s=0.0
b=0.0
while c<l:
poly[i]=poly[i]*(i)
c=c+1
i=i-1
if len(poly)!=1:
poly.remove(0)
return evaluatePoly(poly, x)

Answer 5

these are the codes used to calc val of polynomial and its deriv

Answer 6

def computeRoot(poly,x_0,epsilon):
count=0
while abs(evaluatePoly(poly,x_0))>epsilon:
x1=x_0-(evaluatePoly(poly,x_0)/computeDeriv(poly,x_0))
x_0=x1
return x1

>>> print computeRoot([-13.39, 0.0, 17.5, 3.0, 1.0], 0.1, .0001)

Traceback (most recent call last):
File "<pyshell#58>", line 1, in <module>
print computeRoot([-13.39, 0.0, 17.5, 3.0, 1.0], 0.1, .0001)
File "<pyshell#57>", line 4, in computeRoot
x1=x_0-(evaluatePoly(poly,x_0)/computeDeriv(poly,x_0))
ZeroDivisionError: float division by zero

Answer 7

now solve ma prob pls i have only 30 mints

Answer 8

have you already passed the greader for evaluatePoly and computeDeriv?

Answer 9

yo i have!!

Answer 10

ok
sec

Answer 11

i can upload the screenshots if u want

Answer 12

1st of all why your computederiv has 2 variables? its supposed to be computeDeriv(poly) not (poly,x)

Answer 13

ive modified it yaar cz we need the value of derivative of poly at x_0

Answer 14

im not sure it will pass the grader but .....dunno...ok let me see it like you made it then.

Answer 15

bro when IDLE says its wrong how will grader pass it??
if u can pls gimme ur code il understand my mistake n rem errors frm ma code!

Answer 16

nah you wont :P and im looking into your mistakes right now give me a sec:)

Answer 17

okay but i have only 16 mints left

Answer 18

i am trying to help you and i know u have few time left:)

Answer 19

what im thinking now is why your derivative gives you 0?

Answer 20

thats wat i am thinkin since yesterday

Answer 21

its only 8 mints left m totally stuck

Answer 22

btw your poly remains always the same for every iteration if im not wrong

Answer 23

def computeRoot(poly,x_0,epsilon):
count=0
while abs(evaluatePoly(poly,x_0))>epsilon:
x1=x_0-(evaluatePoly(poly,x_0)/computeDeriv(poly,x_0))
x_0=x1
return x1
in this code i mean

Answer 24

no yaar ive checked by printing evaluatePoly every time its gettin changed

Answer 25

def computeRoot(poly,x_0,epsilon):
count=0
while abs(evaluatePoly(poly,x_0))>epsilon:
print evaluatePoly(poly,x_0)
x1=x_0-(evaluatePoly(poly,x_0)/computeDeriv(poly,x_0))
print x1
x_0=x1
count=count+1
print count
return [x1,count]

>>> print computeRoot([-13.39, 0.0, 17.5, 3.0, 1.0], 0.1, .0001)
-13.2119
3.77609905398
1
475.866222176
2.03984812874
2
121.649030977
0.223007429836
3
23.3521783161
-0.75
4
24.0

Traceback (most recent call last):
File "<pyshell#64>", line 1, in <module>
print computeRoot([-13.39, 0.0, 17.5, 3.0, 1.0], 0.1, .0001)
File "<pyshell#63>", line 5, in computeRoot
x1=x_0-(evaluatePoly(poly,x_0)/computeDeriv(poly,x_0))
ZeroDivisionError: float division by zero

Answer 26

lets say you have f(x)=x^2+34x+8......in every iteration you use this...while you have to use its derivative.....


xn+1=xn−f(xn)f′(xn)

Answer 27

thats ma progress if u giv the code itl be better n i will also be of grt help in future try n understand

Answer 28

its ova times up!

Answer 29

i am not gonna give you full code im sry the point is to learn

Answer 30

u can always learn frm the answer but whateva times up n thanks fr helpin

Answer 31

didnt manage rly to help you...and im sry time is up for you ...but if you want i can still try and resolve this with you...

Answer 32

now can i see ur code??? i can not submit it anymore

Answer 33

about poly i was wrong and you were right...

Answer 34

i told ya ive tried everything
first time in life have i asked some one fr a code :-D

Answer 35

check your messages.

Answer 36

Since you have the time mate it would be nice to sit here with people willing to help you to walk through the problem and understand how it can be solved!

That's my suggestion anyway!

Answer 37

times ova chris but im stilltryin to understand the error in ma code

Answer 38

thanks micro im readin n tryin to understand it

Answer 39

Please come back with specific questions so we can help you!

Answer 40

@ishesh by the way let me know how you will modify your solution by learning from mine:) its always nice to see different ways.

Answer 41

@ishesh no questions at all???

Answer 42

http://dpaste.com/818470/