X-Git-Url: http://nitlanguage.org

diff --git a/lib/standard/math.nit b/lib/standard/math.nit
index 9d2b2bf..1d1437b 100644
--- a/lib/standard/math.nit
+++ b/lib/standard/math.nit
@@ -114,17 +114,66 @@ redef class Int
 end
 
 redef class Float
+
+	# Returns the non-negative square root of `self`.
+	#
+	#     assert 9.0.sqrt == 3.0
+	#     #assert 3.0.sqrt == 1.732
+	#     assert 1.0.sqrt == 1.0
+	#     assert 0.0.sqrt == 0.0
 	fun sqrt: Float is extern "kernel_Float_Float_sqrt_0"
+
+	# Computes the cosine of `self` (expressed in radians).
+	#
+	#     #assert pi.cos == -1.0
 	fun cos: Float is extern "kernel_Float_Float_cos_0"
+
+	# Computes the sine of `self` (expressed in radians).
+	#
+	#     #assert pi.sin == 0.0
 	fun sin: Float is extern "kernel_Float_Float_sin_0"
+
+	# Computes the cosine of x (expressed in radians).
+	#
+	#     #assert 0.0.tan == 0.0
 	fun tan: Float is extern "kernel_Float_Float_tan_0"
+
+	# Computes the arc cosine of `self`.
+	#
+	#     #assert 0.0.acos == pi / 2.0
 	fun acos: Float is extern "kernel_Float_Float_acos_0"
+
+	# Computes the arc sine of `self`.
+	#
+	#     #assert 1.0.asin == pi / 2.0
 	fun asin: Float is extern "kernel_Float_Float_asin_0"
+
+	# Computes the arc tangent of `self`.
+	#
+	#     #assert 0.0.tan == 0.0
 	fun atan: Float is extern "kernel_Float_Float_atan_0"
+
+	# Returns the absolute value of `self`.
+	#
+	#     assert 12.0.abs == 12.0
+	#     assert (-34.56).abs == 34.56
+	#     assert -34.56.abs == -34.56
 	fun abs: Float `{ return fabs(recv); `}
 
+	# Returns `self` raised at `e` power.
+	#
+	#     #assert 2.0.pow(0.0) == 1.0
+	#     #assert 2.0.pow(3.0) == 8.0
+	#     #assert 0.0.pow(9.0) == 0.0
 	fun pow(e: Float): Float is extern "kernel_Float_Float_pow_1"
+
+	# Returns the logarithm of `self`.
+	#
+	#     assert 0.0.log.is_inf == -1
+	#     #assert 1.0.log == 0.0
 	fun log: Float is extern "kernel_Float_Float_log_0"
+
+	# Returns **e** raised to `self`.
 	fun exp: Float is extern "kernel_Float_Float_exp_0"
 
 	#     assert 1.1.ceil == 2.0
@@ -138,11 +187,22 @@ redef class Float
 	#     assert 2.0.floor == 2.0
 	#     assert (-1.5).floor == -2.0
 	fun floor: Float `{ return floor(recv); `}
+
+	# Rounds the value of a float to its nearest integer value
+	#
+	#     assert 1.67.round == 2.0
+	#     assert 1.34.round == 1.0
+	#     assert -1.34.round == -1.0
+	#     assert -1.67.round == -2.0
+	fun round: Float is extern "round"
 	
 	# Returns a random `Float` in `[0.0 .. self[`.
 	fun rand: Float is extern "kernel_Float_Float_rand_0"
-	fun hypot_with( b : Float ) : Float is extern "hypotf"
 
+	# Returns the euclidean distance from `b`.
+	fun hypot_with(b : Float): Float is extern "hypotf"
+
+	# Returns true is self is not a number.
 	fun is_nan: Bool is extern "isnan"
 
 	# Is the float an infinite value
@@ -185,7 +245,30 @@ redef class Sys
 	end
 end
 
+# Computes the arc tangent given `x` and `y`.
+#
+#     assert atan2(-0.0, 1.0) == -0.0
+#     assert atan2(0.0, 1.0) == 0.0
 fun atan2(x: Float, y: Float): Float is extern "kernel_Any_Any_atan2_2"
+
+# Approximate value of **pi**.
 fun pi: Float is extern "kernel_Any_Any_pi_0"
+
+# Initialize the pseudo-random generator with the given seed.
+# The pseudo-random generator is used by the method `rand` and other to generate sequence of numbers.
+# These sequences are repeatable by calling `srand_from` with a same seed value.
+#
+# ~~~~
+# srand_from(0)
+# var a = 10.rand
+# var b = 100.rand
+# srand_from(0)
+# assert 10.rand == a
+# assert 100.rand == b
+# ~~~~
 fun srand_from(x: Int) is extern "kernel_Any_Any_srand_from_1"
+
+# Reinitialize the pseudo-random generator used by the method `rand` and other.
+# This method is automatically invoked at the begin of the program, so usually, there is no need to manually invoke it.
+# The only exception is in conjunction with `srand_from` to reset the pseudo-random generator.
 fun srand is extern "kernel_Any_Any_srand_0"