4 files changed, 28 insertions, 7 deletions
diff --git a/ext/bigdecimal/bigdecimal.c b/ext/bigdecimal/bigdecimal.c
index 2a0aea8b32..95d74b98c2 100644
--- a/ext/bigdecimal/bigdecimal.c
+++ b/ext/bigdecimal/bigdecimal.c
@@ -890,17 +890,21 @@ BigDecimal_add(VALUE self, VALUE r)
 }
 
  /* call-seq:
-  * sub(value, digits)
+  * value - digits   -> bigdecimal
   *
   * Subtract the specified value.
   *
   * e.g.
-  *   c = a.sub(b,n)
   *   c = a - b
   *
-  * digits:: If specified and less than the number of significant digits of the
-  * result, the result is rounded to that number of digits, according to
-  * BigDecimal.mode.
+  * The precision of the result value depends on the type of +b+.
+  *
+  * If +b+ is a Float, the precision of the result is Float::DIG+1.
+  *
+  * If +b+ is a BigDecimal, the precision of the result is +b+'s precision of
+  * internal representation from platform. So, it's return value is platform
+  * dependent.
+  *
   */
 static VALUE
 BigDecimal_sub(VALUE self, VALUE r)
@@ -1516,6 +1520,19 @@ BigDecimal_add2(VALUE self, VALUE b, VALUE n)
     }
 }
 
+/*
+ * sub(value, digits)  -> bigdecimal
+ *
+ * Subtract the specified value.
+ *
+ * e.g.
+ *   c = a.sub(b,n)
+ *
+ * digits:: If specified and less than the number of significant digits of the
+ * result, the result is rounded to that number of digits, according to
+ * BigDecimal.mode.
+ *
+ */
 static VALUE
 BigDecimal_sub2(VALUE self, VALUE b, VALUE n)
 {
@@ -1533,6 +1550,7 @@ BigDecimal_sub2(VALUE self, VALUE b, VALUE n)
     }
 }
 
+
 static VALUE
 BigDecimal_mult2(VALUE self, VALUE b, VALUE n)
 {
@@ -2492,6 +2510,7 @@ BigDecimal_new(int argc, VALUE *argv)
     return VpAlloc(mf, RSTRING_PTR(iniValue));
 }
 
+/* See also BigDecimal::new */
 static VALUE
 BigDecimal_global_new(int argc, VALUE *argv, VALUE self)
 {
diff --git a/ext/bigdecimal/lib/bigdecimal/newton.rb b/ext/bigdecimal/lib/bigdecimal/newton.rb
index 1110652801..db1a5ad99e 100644
--- a/ext/bigdecimal/lib/bigdecimal/newton.rb
+++ b/ext/bigdecimal/lib/bigdecimal/newton.rb
@@ -30,7 +30,7 @@ module Newton
   include Jacobian
   module_function
 
-  def norm(fv,zero=0.0)
+  def norm(fv,zero=0.0) # :nodoc:
     s = zero
     n = fv.size
     for i in 0...n do
@@ -39,6 +39,7 @@ module Newton
     s
   end
 
+  # See also Newton
   def nlsolve(f,x)
     nRetry = 0
     n = x.size
diff --git a/ext/bigdecimal/sample/linear.rb b/ext/bigdecimal/sample/linear.rb
index 88a62ffa71..93d558b539 100644
--- a/ext/bigdecimal/sample/linear.rb
+++ b/ext/bigdecimal/sample/linear.rb
@@ -10,6 +10,7 @@
 #   ruby linear.rb [input file solved]
 #
 
+# :stopdoc:
 require "bigdecimal"
 require "bigdecimal/ludcmp"
 
diff --git a/ext/bigdecimal/sample/nlsolve.rb b/ext/bigdecimal/sample/nlsolve.rb
index 7f729e6aaa..692a5023cc 100644
--- a/ext/bigdecimal/sample/nlsolve.rb
+++ b/ext/bigdecimal/sample/nlsolve.rb
@@ -9,7 +9,7 @@ require "bigdecimal"
 require "bigdecimal/newton"
 include Newton
 
-class Function
+class Function # :nodoc: all
   def initialize()
     @zero = BigDecimal::new("0.0")
     @one  = BigDecimal::new("1.0")