test_cos = ->
	run_test [

		"cos(x)",
		"cos(x)",

		"cos(-x)",
		"cos(x)",

		"cos(b-a)",
		"cos(a-b)",

		# check against the floating point math library

		"f(a,x)=1+cos(float(a/360*2*pi))-float(x)+cos(a/360*2*pi)-x",
		"",

		"f(0,1)",			# 0
		"1",

		"f(90,0)",			# 90
		"1",

		"f(180,-1)",			# 180
		"1",

		"f(270,0)",			# 270
		"1",

		"f(360,1)",			# 360
		"1",

		"f(-90,0)",			# -90
		"1",

		"f(-180,-1)",			# -180
		"1",

		"f(-270,0)",			# -270
		"1",

		"f(-360,1)",			# -360
		"1",

		"f(45,sqrt(2)/2)",		# 45
		"1",

		"f(135,-sqrt(2)/2)",		# 135
		"1",

		"f(225,-sqrt(2)/2)",		# 225
		"1",

		"f(315,sqrt(2)/2)",		# 315
		"1",

		"f(-45,sqrt(2)/2)",		# -45
		"1",

		"f(-135,-sqrt(2)/2)",		# -135
		"1",

		"f(-225,-sqrt(2)/2)",		# -225
		"1",

		"f(-315,sqrt(2)/2)",		# -315
		"1",

		"f(30,sqrt(3)/2)",		# 30
		"1",

		"f(150,-sqrt(3)/2)",		# 150
		"1",

		"f(210,-sqrt(3)/2)",		# 210
		"1",

		"f(330,sqrt(3)/2)",		# 330
		"1",

		"f(-30,sqrt(3)/2)",		# -30
		"1",

		"f(-150,-sqrt(3)/2)",		# -150
		"1",

		"f(-210,-sqrt(3)/2)",		# -210
		"1",

		"f(-330,sqrt(3)/2)",		# -330
		"1",

		"f(60,1/2)",			# 60
		"1",

		"f(120,-1/2)",			# 120
		"1",

		"f(240,-1/2)",			# 240
		"1",

		"f(300,1/2)",			# 300
		"1",

		"f(-60,1/2)",			# -60
		"1",

		"f(-120,-1/2)",			# -120
		"1",

		"f(-240,-1/2)",			# -240
		"1",

		"f(-300,1/2)",			# -300
		"1",

		"f=quote(f)",
		"",

		"cos(arccos(x))",
		"x",

		# bug fix for version 119

		"cos(1/12*pi)",
		"cos(1/12*pi)",

		"cos(arctan(4/3))",
		"3/5",

		"cos(-arctan(4/3))",
		"3/5",

		# phase

		"cos(x-8/2*pi)",
		"cos(x)",

		"cos(x-7/2*pi)",
		"-sin(x)",

		"cos(x-6/2*pi)",
		"-cos(x)",

		"cos(x-5/2*pi)",
		"sin(x)",

		"cos(x-4/2*pi)",
		"cos(x)",

		"cos(x-3/2*pi)",
		"-sin(x)",

		"cos(x-2/2*pi)",
		"-cos(x)",

		"cos(x-1/2*pi)",
		"sin(x)",

		"cos(x+0/2*pi)",
		"cos(x)",

		"cos(x+1/2*pi)",
		"-sin(x)",

		"cos(x+2/2*pi)",
		"-cos(x)",

		"cos(x+3/2*pi)",
		"sin(x)",

		"cos(x+4/2*pi)",
		"cos(x)",

		"cos(x+5/2*pi)",
		"-sin(x)",

		"cos(x+6/2*pi)",
		"-cos(x)",

		"cos(x+7/2*pi)",
		"sin(x)",

		"cos(x+8/2*pi)",
		"cos(x)",
	]