Matlab Demos in the Week-6 Lecture

Contents

The defects of the bisect program in NCM
A modified bisect program
Zeroin algorithm

The defects of the bisect program in NCM

% Test the bisect.m for a problem with root of zero.
f=@(x) sin(x);
a= -1; b= 2;
bisect     % This makes the dead loop. Have to kill it with Ctrl+C.

k
a
b

k =

     4656634

a =

     0

b =

  4.9407e-324

A modified bisect program

[x, k]= my_bisect(f, [a, b])

I'm lucky!

x =

     0


k =

        1074

Zeroin algorithm

fzerogui

ans =

start       0.0000000000000000
start       3.0000000000000000
secant      0.7142857142857143
bisect      1.8571428571428572
iqi         2.4063616984279301
secant      2.0543530213726049
iqi         2.0961473339210830
secant      2.0945147956931258
secant      2.0945514486033541
iqi         2.0945514815423278
secant      2.0945514815423265