It seems converting a Q matrix to a Float Matrix takes high-degree polynomial time at best. Is this a bug? If so, is there any way to work around it? I don’t remember having this problem on earlier versions (I am using 1.01). Granted my laptop is pretty slow, but this is worse than matrix inversion…

RalphAS on the GitHub issue thread ( # 29846 ) noted that we can drop the type parameter and recover performance, e.g. writing Matrix{Float64}(f.Q). This workaround fixed the slowness in my code, so I will count the question as solved.

I am seeing similar behavior in 1.0 on a Windows 10 machine. I would say this is a bug. Unless someone else sees an obvious problem with your code, I suggest that you open an issue.

[image] QR decomposition in julia 2x slower than octave Performance I suspect they may be doing different things. I don’t know what qr method Octave calls when no output arguments are provided, but my guess is that it’s just doing the 1st phase (computing the Householder r…

QR Decomposition Extremely Slow

General Usage

jpsamaroo October 30, 2018, 2:26am 3

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QR Decomposition Extremely Slow

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