Cody

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

Solution 1938589

Submitted on 16 Sep 2019 by Augusto Mazzei
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### Test Suite

Test Status Code Input and Output
1   Pass
assert(isempty(regexp(fileread('Rosenbrock_banana.m'),'assert.m')))

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

value = 1 gradient = -2 0

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

value = 0 gradient = 0 0

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

value = 400 gradient = 800 -400

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

value = 29 gradient = -204 -100

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

value = 1 gradient = -2 0

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

value = 1 gradient = -2 0

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

value = 0 gradient = 0 0

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

value = 0 gradient = 0 0

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)))

value = 267.6200 gradient = 1.0e+03 * -1.2294 -0.3220