Doc [ci skip]

doc/tutorial/floats.rst

@@ -0,0 +1,69 @@
+Floating Point Numbers
+======================
+
+Floating point literals are local approximations to reals.
+Local means close to zero. Floats are dense near zero and
+loose precision far from it.
+
+Type
+----
+
+We lift the main floating point type, `double` from C.
+
+.. code-block:: felix
+
+    type double = "double";
+
+It is a double precision floating point representation
+usually conformat to IEEE specifications.
+
+Literals
+--------
+
+Floating literals have two parts, a decimal number
+known as the mantissa, and a power of 10 known as the
+exponent.
+
+.. code-block:: felix
+
+    12.34
+    12.34E-4
+
+The mantissa must contain a decimal point with a digit on either
+side. The exponent is optional, and consists of the letter `E`
+or `e` followed by a small decimal integer literal, or a + sign
+or minus sign, and a small decimal integer literal.
+
+If the exponent is present, the mantissa is multiplied by
+10 raised to the power of the signed integer part exponent.
+
+Operations
+----------
+
+Floating numbers support negation with prefix `-`, addition
+with infix `+`, subtraction with infix `-`, multiplication
+with infix `*` and division with infix `/` as well as
+many other operations given by functions in the library.
+
+It is also possible to perform comparisons, equality `==`,
+inequality `!=`, less than `<`, less than or equal to `<=`,
+greater than `>` and greater than or equal to `>=`. However
+these comparisons reflect floating point arithmentic
+which only approximates real arithmetic. Do not be suprised
+if the formula
+
+.. code-block:: felix
+
+   1.0 / 3.0 * 3.0 == 1.0
+
+is false. To remedy this properly requires a deep knowledge
+of numerical analysis. Felix helps by providing the function
+`abs` which can be used like this:
+
+.. code-block:: felix
+
+  abs ( 1.0 / 3.0 * 3.0 - 1.0) < 1.0e-3
+
+
+to check the result is with about 3 decimal places of 1.0.
+

doc/tutorial/index.rst

@@ -11,7 +11,9 @@ Contents:
    :maxdepth: 2
 
    hello 
+   logic
    integers
+   floats 
    strings
    pythagoras
    guiindex 

doc/tutorial/logic.rst

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+Logic Type Bool
+===============
+
+Felix provides a type for simple logic which tradiationally
+is called `bool` after mathematician George Bool.
+
+Type
+----
+
+We lift the type from C++ as usual:
+
+.. code-block:: felix
+
+    type bool = "std::bool";
+
+
+Constants
+---------
+
+There two predefined constants, `true` and `false`.
+
+Operations
+----------
+
+The prefix operator `not` provides negation, infix
+`and` conjunction, and infix `or` disjunction,
+with weak precedences, of decreasing strength.
+
+.. code-block:: felix
+
+    not a and b or c
+
+is parsed as
+
+.. code-block:: felix
+
+    ((not a) and b) or c
+
+
+These operators are all weaker than the comparisons they often
+take as arguments, so that
+
+
+.. code-block:: felix
+ 
+    a < b and b < c
+
+is parsed as
+
+.. code-block:: felix
+ 
+    (a < b) and (b < c)
+
+
+
+
+