2. My name’s Zhongke Chen(陈忠克)
Python, C/C++ Coder
I worked for Wenzhou University, Virtuos
Games, Ericsson
I majored in EE (Multimedia Analysis)
Twitter, Sina Weibo: @ch3n2k
Monday, June 24, 13
21. Algorithm
make a guess G
improve the guess by averaging G and x/G
keep improving the guess until it’s good
enough
use 1 as an initial guess
Monday, June 24, 13
28. (DEFINE (FIXED-POINT f guess)
(DEFINE (CLOSE-ENOUGH? u v)
(< (ABS (- u v)) 0.0001))
(DEFINE (ITER OLD NEW)
(IF (CLOSE-ENOUGH? OLD NEW)
NEW
(ITER NEW (f NEW))))
(ITER guess (f guess)))
Higher Order Function
Monday, June 24, 13
29. Newton’s method converges more rapidly
find a y that f(y) = 0
start a guess y0,
yn+1 = yn - f(yn)/f’(yn)
Monday, June 24, 13
30. (DEFINE (NEWTON f guess)
(DEFINE DF (DERIV f))
(FIXED-POINT
(LAMBDA (y) (- y (/ (f y)(DF y))))
guess))
(DEFINE DERIV
(LAMBDA (f)
(LAMBDA (x)
(/ (- (f (+ x dx))(f x)) dx))))
(DEFINE dx 0.00001)
Monday, June 24, 13