setup

test-error acos(1.0001)
test-error acos(-1.0001)

test acos(-1) is pi
test acos(-0.5) is 2 * pi / 3
test acos(0) is pi / 2
test acos(0.5) is pi / 3
test acos(1) is 0

//repeat with i = -1 to 1 step 0.01
//	test cos(acos(i)) is i
//end repeat

teardown