## Spivak

I hope that almost all of this is self-explanatory.
The 'S' in **S**pivak is supposed to stand for 'simple'.
### 0. Downloading

The program is distributed in a disk image (.dmg) file.
Save the .dmg to disk; double click to open it, then drag
the application to your desktop, or Applications folder.
### 1. Entering formulas

The three wide fields at the top, center of the window are
the components of the parametrization.
The formula parser knows the following functions:
sin cos tan
sinh cosh tanh
arcsin arccos arctan
arcsinh arccosh arctanh
exp ln
and the following binary operations, with their usual precedence:
+ - * / ^
You can refer to the constants
**pi** and **e**
by name in your formulas. Use 'u' and 'v' for your parameters; other
variable names will be treated as if they are zero.
### 2. Choosing a point (and direction)

Click and drag in the upper left ('domain') window to choose a point
in the (u,v) plane, and you'll see the corresponding point marked on
the surface in the main window.
To choose a direction (for a geodesic, or tangent line), Control-click
in the domain window. You'll mark a green reference point, and the implied
direction vector is from the white point toward the green point.
You can also use the vertical slider at the far right of the screen
to change the direction vector.
### 3. Adjusting the view

You can click and drag in the main window to rotate the view, and you
can Control-click-and-drag to zoom in and out. The small slider on
the right controls the size of any decorations you're currently drawing.
### 4. Writing the rest of the documentation

This is currently happening.