Merge pull request #26 from rharbird/new_pxt

More formatting changes

docs/source/sine.rst

@@ -11,13 +11,13 @@ As it happens, many things in biology happen like sine waves. That's true for th
 What this means is the change in angle is slower the closer you get to 180° and to 0°. So it starts slowly, then gets faster, then slows down, changes direction, and so on.
 
 The function for the angle is:
-``angle = 90 + 90 * Math.sin(2 * PI * running_time / 4000)``
+``angle = 90 + 90 * Math.sin(2 * PI * running_time() / 4000)``
 
 Note: the ``Math.sin()`` function requires that the number of degrees is expressed as radians. 360° is 2 * PI radians.
 
-* ``running_time`` is the amount of time since the micro:bit was turned on in ms.
+* ``running_time()`` is the amount of time since the micro:bit was turned on in ms.
 * The 4000ms is the amount of time it takes to go from angle 0° back to 0° again. Make this number bigger to go slower.
-* Sine values vary between 0 and 1 so the angle varies between 0° and 180° as things stand. The **90 *** is the amplitude of the wave and here we want it to go through all 180° of motion. Make this smaller if you want less; if the value was, say 40, then the movement would vary between 60° and 130°.
-* The **90 +** is the centre position position of the movement. The servo moves equally either side of that centre. You could choose to centre the movement in a different place. If this was say, 100 and the amplitude was 40 then the servo would move between 60° and 140°.
-
+* Sine values vary between 0 and 1 so the angle varies between 0° and 180° as things stand. The ``90 *`` is the amplitude of the wave and here we want it to go through all 180° of motion. Make this smaller if you want less; if the value was, say 40, then the movement would vary between 60° and 130°.
+* The ``90 +`` is the centre position position of the movement. The servo moves equally either side of that centre. You could choose to centre the movement in a different place. If this was say, 100 and the amplitude was 40 then the servo would move between 60° and 140°.
+* You could create variables for amplitude and time period, say ``A`` and ``T``, with another for the centre ``C``. This makes the formula: ``angle = C + A * Math.sin(2 * PI running_time() / T)
 Congratulations! You made an oscillator. The nice thing about sinusoidal oscillators is that putting things out of phase is easy. Say you wanted two sine waves 90° out of phase then set:``angle1`` = sin(t) and ``angle2`` = sin(t + 90)