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Solution 62853

Submitted on 18 Mar 2012 by Charles Eger

Correct

126Size
Leading solution size is 76.
This solution is locked. To view this solution, you need to provide a solution of the same size or smaller.

Test Suite

Test
Code Input and Output
1
Pass
 
%%
% Rosenbrock's banana function
F=@(x) 100*(x(2)-x(1).^2).^2 + (1-x(1)).^2;
gradF=@(x) [100*(4*x(1).^3-4*x(1).*x(2))+2*x(1)-2; 100*(2*x(2)-2*x(1).^2)];
x0 = [-1.9; 2.0];
x1=[
   -1.4478
    2.1184];
x2=[
    1.7064
    2.9446];
f1=6.0419;
f2=0.6068;
[xmin,fmin]=SteepestDescent(F,gradF,x0,0.01,1)
assert(norm(xmin-x1)<0.2||norm(xmin-x2)<0.2)
assert( abs(fmin-f1)<0.5|| abs(fmin-f2)<0.5) % 2 local min
xmin =
    1.7158
    2.9470
fmin =
    0.5133
2
Pass
 
%%
% Rosenbrock's banana function
F=@(x) 100*(x(2)-x(1).^2).^2 + (1-x(1)).^2;
gradF=@(x) [100*(4*x(1).^3-4*x(1).*x(2))+2*x(1)-2; 100*(2*x(2)-2*x(1).^2)];
x0 = [0; 0];
xcorrect=[1;1];
fcorrect=0;
[xmin,fmin]=SteepestDescent(F,gradF,x0) % 20 iterations default
assert(norm((xmin-xcorrect),inf)<1)
assert(abs(fmin-fcorrect)<0.8);
xmin =
    0.3669
    0.1346
fmin =
    0.4008
3
Pass
 
%%
% Rosenbrock's banana function
F=@(x) 100*(x(2)-x(1).^2).^2 + (1-x(1)).^2;
gradF=@(x) [100*(4*x(1).^3-4*x(1).*x(2))+2*x(1)-2; 100*(2*x(2)-2*x(1).^2)];
x0 = [1.1; 0.9];
xcorrect=[1;1];
fcorrect=0;
[xmin,fmin]=SteepestDescent(F,gradF,x0,1e-2,2000)
assert(isequal(round(xmin),xcorrect))
assert(isequal(round(fmin),fcorrect))
xmin =
    0.9918
    0.9836
fmin =
   6.7296e-05