Allclose - How to check if two arrays are closed in Julia

Question

In numpy, you can do np.allclose(A, B) to see if arrays A and B are closed.

Is there any function in Julia?

Answer 1

(For an obsolete version of this answer, see the horizontal line below.)

The version of the isapprox array was introduced in Julia 0.4, so now you can write:

 isapprox(A, B) 

As in the scalar case, you can specify relative rtol tolerance and absolute atol tolerance as keyword arguments.

But note that unlike NumPy allclose (and the previous solution to this answer below), array- isapprox first calculates the norm and then decides the resulting value. (Apparently, the check isapprox pointwise is incorrect .) By default, the Frobenius norm is vecnorm , but you can override this behavior with the norm keyword argument.

By the way, as mentioned in the linked pull request, in tests you can write @test isapprox(A, B) , so @test_approx_eq now deprecated and deprecated as 0.6. In addition, there exists A ≈ B , which is equivalent to isapprox(A, B) and can be used as any comparison operator: a < b ≈ c ≤ d .

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For reference, this is the previous, deprecated version of this post:

For single numbers, isapprox is isapprox . If you want to extend this to an elementary comparison on Array s, you can use:

 all(x -> isapprox(x...), zip(A, B)) all(x -> isapprox(x...), zip(A, A + 1e-5)) # => false all(x -> isapprox(x...), zip(A, A + 1e-6)) # => true 

Answer 2

There is no function named allclose that comes with Julia:

 julia> allclose ERROR: allclose not defined 

I don’t know if the existing Julia function provides the functionality you need, but based on numpy.allclose you can implement one documentation (complete with keyword arguments ):

 function allclose(a, b; rtol = 1e-5, atol = 1e-8) return all(abs(a - b) .<= (atol + rtol * abs(b))) end 

Tests on the Julia command line:

 julia> A = rand(5, 5) 5x5 Array{Float64,2}: 0.0833821 0.722352 0.474616 0.0997349 0.352403 0.557657 0.199624 0.748646 0.838296 0.0396182 0.9716 0.230623 0.215245 0.689457 0.261951 0.64731 0.0799202 0.877895 0.582062 0.601394 0.875966 0.776157 0.664024 0.0996859 0.12747 julia> allclose(A, A + 1e-4) false julia> allclose(A, A + 1e-6) false julia> allclose(A, A + 1e-8) true julia> allclose(A, A + 1, rtol = 1) true 

Answer 3

If you are writing tests, using Base.Test and then @test_approx_eq AB should work.