% Q11 Page50 Section 2.2
i = [1:14] ;
hinv = 2.^i ;
h = hinv.^(-1) ;
x = pi/4 ;
val = 1/(1+x^2) ;
f1x = (8*atan(x+h)-8*atan(x-h)-atan(x+2*h)+atan(x-2*h))./(12*h) ;
error = abs(f1x-val) ;
semilogy(hinv,error) ;
xlabel('h inverse') ;
ylabel('log error') ;
minError = min(error) ;
indexME = find(minError == error)
fprintf('The power of 2 is -%d or The value of h for minimum eror is 1/%d',indexME,2^(indexME)) ;

indexME =

    11

The power of 2 is -11 or The value of h for minimum eror is 1/2048

Published with MATLAB® 7.0