OpenEuphoria

mathematics on sequences

• Posted by Hayden McKay <hmck1 at dodo.com.au> Mar 07, 2005
• 478 views

As you readers probably know I'm currently takeing a crash coarse with matrices
and
2d-3d rotation. Any way I found some thing interesting and I was wondering if
someone could explain the reason why.

below are two test cases of a routine that would rotate
(x) left--right and (y) up--down

test_1() benchmarked a wopping ~0.66xxxxxx while test_2() came in at
~0.06xxxxx on my pentium III 550. You would assume test_1() to be the
fastset but this is not the case.

I also ran another test ie: repeat({100,100},10000)+array and the same in
a for..do..end for loop but they came in with identical times. wiered since
test_1() and test_2() have different times. I'm guessing this may have
something to do with EX.EXE FPU emulated sequence mathematics compared
to EX.EXE FPU emulated atom mathematics.

-- nb the matrix is only a dummy test matrix.
-- (you cant use the routines to rotate a real coord array)

sequence coords coords=repeat({rand(800),rand(600)},10000)
sequence matrix matrix={{1.123456789,-1.123456789},
                       {-1.123456789, 1.123456789}}

function test_1()
    sequence row_1, row_2

    row_1=repeat(matrix[1],10000)*coords
    row_2=repeat(matrix[1],10000)*coords
    coords=(row_1+row_2)
    return coords

end function

function test_2()

    for i=1 to 10000 do
        coords[i][1]=(coords[i][1]*matrix[1][1])+(coords[i][1]*matrix[2][1])
        coords[i][2]=(coords[i][2]*matrix[1][2])+(coords[i][1]*matrix[2][2])
    end for
    return coords

end function

include machine.e
tick_rate(100)

atom t
sequence s

t=time()
s=test_1()
?t-time()
t=time()
s=test_2()
?t-time()