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Rafael S.T. Vieira

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Rafael S.T. Vieira submitted a Comment to Problem 47043. Find the Arc Length of the Curve Defined by the Parametric Functions

Recommended https://blogs.mathworks.com/cleve/2013/10/14/complex-step-differentiation/

on 23 Oct 2020 at 15:13

Rafael S.T. Vieira submitted a Comment to Problem 46918. Numerical differentiation with high precision

Nice problem. And thanks for the tip about Cleve's article and paper.

on 23 Oct 2020 at 5:24

Rafael S.T. Vieira submitted Solution 3341093 to Problem 47008. NaN

on 23 Oct 2020 at 4:57

Rafael S.T. Vieira submitted Solution 3341088 to Problem 47038. imaginary

on 23 Oct 2020 at 4:57

Rafael S.T. Vieira submitted Solution 3341083 to Problem 47033. Real

on 23 Oct 2020 at 4:57

Rafael S.T. Vieira submitted Solution 3341078 to Problem 47028. Size

on 23 Oct 2020 at 4:56

Rafael S.T. Vieira submitted Solution 3341063 to Problem 47013. Swap

on 23 Oct 2020 at 4:55

Rafael S.T. Vieira submitted a Comment to Solution 3314043

No problem. And congratulations :)

on 22 Oct 2020 at 7:15

Rafael S.T. Vieira submitted a Comment to Solution 3267838

Excellent, Ratul, congrats. And No problem.

on 22 Oct 2020 at 6:38

Rafael S.T. Vieira submitted a Comment to Problem 46963. Roots, Bloody Roots: part 2/2

Hi, Svyatoslav, I've figured out what the problem was. It appears there is a small error < 1e-10 between our interpolation methods. This error wouldn't matter regularly, but since we are doing gamma correction, that error gets magnified. To fix this, I've changed the problem description to request that all interpolations be rounded to 4 decimal places. This seems to resolve the issue (since there will be no error to be magnified by the gamma correction).

on 22 Oct 2020 at 6:23

Rafael S.T. Vieira submitted a Comment to Solution 3314043

If you round both results from linspace to 4 decimal places, this solution will pass the test suite.

on 22 Oct 2020 at 6:21

Rafael S.T. Vieira submitted a Comment to Problem 930. 1D DCT-II transform.

A fair warning to the challenger: the requested DCT-II is the orthogonal version, which means it needs to be multiplied by sqrt(2/N) where N is the size of the row, and the first element of the DCT x0 needs to be multiplied by 1/sqrt(2). It took me a while to understand. Wikipedia's formula is almost right, but it is missing those terms, which are mentioned only further below. Look at MATLAB's documentation (DCT-2), https://www.mathworks.com/help/signal/ref/dct.html, to find the proper formula.

on 22 Oct 2020 at 1:16

Rafael S.T. Vieira submitted a Comment to Problem 46833. Roots, Bloody Roots: part 1/2

Svyatoslav Golousov, the real axis pointing left is only a convention. However, I will change the problem description later to explain it as I did on the next one. And I will think of a way to measure the similarity between images. I agree it's essential to provide better feedback; thanks for the suggestion.

on 22 Oct 2020 at 1:14

Rafael S.T. Vieira submitted a Comment to Problem 46963. Roots, Bloody Roots: part 2/2

No problem, Svyatoslav, I will take a look tomorrow.

on 22 Oct 2020 at 0:47

Rafael S.T. Vieira liked Problem 45182. Takuzu row

on 21 Oct 2020 at 22:22

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