If I compare this Julia code: module Testing function performance_test() range = 1:2000000; steering_vectors = complex(randn(4,11), randn(4,11)); sum_signal = zeros(Complex{Float64}, 4, length(range)); for i = 1:11 carrier_signal = map(x -> exp(2im * pi * 1.023e6 * x / …

[image] TsurHerman: took out: Don’t do that since it has been repeatedly mentioned in the thread that this can’t be done in the real code and it’s actually where most of the time is spent.

[image] yuyichao: Don’t do that since it has been repeatedly mentioned in the thread that this can’t be done in the real code and it’s actually where most of the time is spent. well for the sin cos performance ,it was discussed already in this thread pointing out to better implementations. I…

btw: sincos as function to provide sin and cos for the same argument should afair be available as operation in the FPU. I don’t know which lib-m exposes this, but i’m pretty sure matlab detects the exp(i * pi* something) and uses this.

It’s a slow x87 instructions so I don’t think anything is using it.

Calling exp(im...) is extremely common in my line of work. An expim(::Real) function or something like that would be quite useful.

[image] RoyiAvital: @DNF , Could you tell the timing of the run when you used Julia’s sin and cos? The difference is marginal. Sometimes I see no difference, and sometimes it saves <1 sec. Which is odd because the timing of carrier_signal .= exp.(im.*α) vs carrier_signal .= complex.(cos.(α)…

[image] giordano: You’re looking for cis function. Indeed I am! Thanks! I also see that There is an AppleAccelerate.cis! function. Using this drops the single-threaded runtime to 325ms.

So it seems that the biggest gain is avoiding exponent of complex number and working efficiently with memory. I conclude that since @zsoerenm in his post managed to beat MATLAB using Julia (Even his result without Yepp). Which means, as I guessed at first, this was all about efficiency of the code…

[image] RoyiAvital: Priority number 1 is to minimize the gap between the code generated by Julia in Vector Form to what Julia can do in non vectorized form. See v0.6 + future PRs for stack-allocated views. This has already been mentioned.

Why is this Julia code considerably slower than Matlab

New to Julia

giordano March 1, 2017, 7:52pm 49

You’re looking for cis function.

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Why is this Julia code considerably slower than Matlab

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