7/7/2023 0 Comments Mathworks matlab 2016![]() In the first decade of MATLAB, expert users typically used an indexing technique called Tony's Trick to do the expansion. Instead, you had to expand ma to be the same size as A and then do the subtraction. The mean function conveniently gives you each of the column means: ma = mean(A)īut since ma is not the same size as A and is not a scalar, you couldn't just subtract ma from A directly. A = rand(3,3)Īnd suppose you want to modify each column of A by subtracting the column's mean. Subtracting Column Means: Decade by Decade Subtracting Column Means: Decade by Decade.For the next part of the discussion, I'll use an example that almost everyone at MathWorks uses when talking about this topic: subtracting the column means from a matrix. ![]() I will talk about how it works and why we did it. Today I want to explain this new implicit expansion behavior of MATLAB arithmetic operators (and some functions). I say "implicitly" because MATLAB does not actually make an in-memory copy of the expanded vector. In the new release, though, MATLAB implicitly expands the vector v to be the same size as the matrix RGB and then carries out the elementwise multiplication. ![]() In R2016a and older MATLAB releases, that line of code produced an error:Įrror using. ![]() I needed to multiply each column of RGB by the corresponding element of v, like this: RGB_c = īut since I was using an internal developer build of MATLAB R2016 (released on September 14), I didn't type the code above. At one point in the code, I had a Px3 matrix called RGB, which contained P colors, one per row. He has been heavily involved in image processing capabilities in our tools and more recently has also contributed substantially to designing additions and improvements to the MATLAB language.Įarlier this summer, I was writing some color-space conversion code. With pleasure, I introduce today's guest blogger, my colleague, Steve Eddins. ![]()
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