Cody

# Problem 481. Rosenbrock's Banana Function and its derivatives

Solution 60128

Submitted on 12 Mar 2012 by Thomas Gorman
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### Test Suite

Test Status Code Input and Output
1   Pass

2   Pass
%% x = [0; 0]; assert(isequal(Rosenbrock_banana(x),1))

Hessian = 2 0 0 200

3   Pass
%% x = [1; 1]; assert(isequal(Rosenbrock_banana(x),0))

Hessian = 802 -400 -400 200

4   Pass
%% x = [1; -1]; assert(isequal(Rosenbrock_banana(x),400))

Hessian = 1602 -400 -400 200

5   Pass
%% x = [-1; 0.5]; assert(isequal(Rosenbrock_banana(x),29))

Hessian = 1002 400 400 200

6   Pass
%% x = [0; 0]; [~,grad]=Rosenbrock_banana(x); assert(isequal(grad,[-2; 0]))

Hessian = 2 0 0 200

7   Pass
%% x = [0; 0]; [~,~,Hess]=Rosenbrock_banana(x); assert(isequal(Hess,diag([2, 200])))

Hessian = 2 0 0 200

8   Pass
%% x = [1; 1]; [~,grad]=Rosenbrock_banana(x); assert(isequal(grad,[0; 0]))

Hessian = 802 -400 -400 200

9   Pass
%% x = [1; 1]; [~,~,Hess]=Rosenbrock_banana(x); assert(isequal(Hess,[802, -400; -400, 200]))

Hessian = 802 -400 -400 200

10   Pass
%% x = [-1.9; 2]; correct_value = 267.6200; correct_grad = -1e3*[1.2294; 0.3220]; correct_Hess = [3534, 760; 760, 200]; [val,grad,Hess]=Rosenbrock_banana(x); assert(isequal(str2num(num2str(val)),correct_value)) assert(isequal(str2num(num2str(grad)),correct_grad)) assert(all(max(abs(Hess-correct_Hess)<1e-8)))

Hessian = 3534 760 760 200