--[[

/*******************************************************

* Copyright (c) 2014, ArrayFire

* All rights reserved.

*

* This file is distributed under 3-clause BSD license.

* The complete license agreement can be obtained at:

* http://arrayfire.com/licenses/BSD-3-Clause

********************************************************/

]]

-- Modules --

local lib = require("arrayfire")

lib.main(function()

-- 5x5 derivative with separable kernels

local h_dx = {1. / 12, -8. / 12, 0, 8. / 12, -1. / 12} -- five point stencil

local h_spread = {1. / 5, 1. / 5, 1. / 5, 1. / 5, 1. / 5}

local function fail (left, right)

return lib.max("f32", lib.abs(left - right)) > 1e-6

end

-- setup image and device copies of kernels

local img = lib.randu(640, 480)

-- device kernels

local dx = lib.array(5, 1, h_dx) -- 5x1 kernel

local spread = lib.array(1, 5, h_spread) -- 1x5 kernel

local kernel = lib.matmul(dx, spread) -- 5x5 kernel

local full_out, dsep_out

lib.printf("full 2D convolution: %.5f seconds", lib.timeit(function() full_out = lib.convolve2(img, kernel) end))

lib.printf("separable, device pointers: %.5f seconds", lib.timeit(function() dsep_out = lib.convolve(dx, spread, img) end))

-- ensure values are all the same across versions

assert(not fail(full_out, dsep_out), "full != dsep")

end)