Cody

Problem 963. We love vectorized solutions. Problem 1 : remove the row average.

Solution 1943269

Submitted on 19 Sep 2019
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Test Suite

Test Status Code Input and Output
1   Pass
x = [ 0 1 ; 2 3 ] ; timer=tic; y = remove_average_vectorized(x); duration=toc(timer) % You can probably pass this test with a for loop. assert(duration<0.1,sprintf('Time used %2.3f\n',duration));

ans = -0.5000 0.5000 -0.5000 0.5000 duration = 2.9700e-04

2   Fail
x = [ 1:9999 ; 2:10000 ; [ zeros(1,9998) 9999 ] ]; x = repmat(x,1000,1); y_correct = [ -4999:1:4999 ; -4999:1:4999 ; [ repmat(-1,1,9998) 9998 ] ]; y_correct = repmat(y_correct,1000,1); y = remove_average_vectorized(x); assert(isequal(y,y_correct));

Error using repmat Requested 3000000x9999 (223.5GB) array exceeds maximum array size preference. Creation of arrays greater than this limit may take a long time and cause MATLAB to become unresponsive. See array size limit or preference panel for more information. Error in remove_average_vectorized (line 6) repmat(x,1000,1) Error in Test2 (line 5) y = remove_average_vectorized(x);

3   Fail
x = [ 1:9999 ; 2:10000 ; [ zeros(1,9998) 9999 ] ]; x = repmat(x,1000,1); timer=tic; y = remove_average_vectorized(x); duration=toc(timer) % A decent vectorized solution should take around 1 second. assert(duration<2,sprintf('Time used %2.3f\n',duration));

Error using repmat Requested 3000000x9999 (223.5GB) array exceeds maximum array size preference. Creation of arrays greater than this limit may take a long time and cause MATLAB to become unresponsive. See array size limit or preference panel for more information. Error in remove_average_vectorized (line 6) repmat(x,1000,1) Error in Test3 (line 4) y = remove_average_vectorized(x);