TABULA - Getting Started

Introduction

TABULA is a 21-century scientific calculator.

• It lets you build and operate ttables (=TABULA-tables).

• It knows about units and lets you add feet to metres (but not of course feet to seconds!).
• It lets you change an item's units from feet to metres, or to any other unit of length it knows about. (Ditto all sets of compatible units.)
• It backfits changed values to both calculated and non-calculated items, provided it can do so.
• It has a library of constants and formulas, so you don't have to type these by hand. You can add to this library yourself.

To date, TABULA is available for j602. (Versions for j701 JHS and JGTK are under development.)

Install and run TABULA

Using the j602 Package Manager (menu: Run > Package Manager...) install the addons:

• math/uu, math/cal, math/tabula.

Enter:

   load 'math/tabula'

A new window appears:

Alter the value of item 1

Click on item 1. Its value appears in the input field.

Type-in (or overtype with) a new value and press Enter.

• Item 1 changes its value, and so do all items which depend on it (viz. 2, 3, 4).

  Changed values get flagged with the symbol @

To undo the change: click . To redo the change, Shift-click .

• Shift-click means: hold down the Shift key and click the icon .

Another way to alter the value of item 1

Select item 1.

• ...means: click on item 1 to select it.

• Click to zero its value.

• Shift-click to set its value to 1.

• Click to increase its value by 1. (Shift-click to decrease.)

• Click to increase its value by 1%. (Shift-click to decrease.)

  OBSERVATION: a tool icon with red in it means holding down Shift will modify the behavior (usually in the obvious way).

Alter the value of item 2

Yes, unlike in Excel you can alter the value of a calculated item too!

• Suitable changes get backfitted to the feeder items, and other dependent items change too.

It's a good idea to start with a fresh copy of the SAMPLE ttable. To reload it, Shift-click .

Click on item 2. Its value (0.841) appears in the input field.

Now replace it with the value: 1.

• eg Shift-click .

You now see:

plot test
  ┌ ┌  1 @      1.571 rad  angle
┌ │ └> 2 @      1.000 /    sine
├ └>   3 @   3.357E-5 /    cosine
└>     4 @      1.000 /    sin+cos

The flag: @ shows that all items have changed. To compare changes, alternately click and shift-click .

You see that item 1 changes to some value that yields the sine required (=1). The new value is then used to compute the cosine (item 3) and item 4 is recalculated from 2 and 3.

You also see that item 3 has changed to a very low value, but not quite 0. This happens here because the backfitting algorithm is only approximate.

Not every value you insert for item 2 will be accepted. Thus entering the value: 99 will trigger the error message:

• item: 2 resists value: 99

As you'll recall, the sine of an angle cannot exceed 1.

• Also the backfit algorithm may fail... but we're making it better and better.

  HINT: if a calculated item will not accept a given value you offer to it, try changing its existing value by a small amount, eg by use of . You may be able to persuade it to accept the desired value by approaching it in small(ish) steps.

Create a new calculated line

Item 4 is the sum of items 2 and 3. Let's create a new line like it.

Select lines 2 and 3 only.

• In Windows: click on line 1 to deselect it. Then click on lines 2 and 3.

  On the Macintosh, click 2 (which deselects all other lines) then hold ⌘ down and click 3.

  To deselect all other lines, click on line 0 (the title). In Windows you must click on line 0 again to deselect it before it lets you select another line.

Having selected 2 and 3, click .

• A new line (5) appears. You now see:

plot test
    ┌ ┌  1        1.000 rad  angle
┌ ┌ │ └> 2        0.841 /    sine
├ ├ └>   3        0.540 /    cosine
│ └>     4        1.382 /    sin+cos
└>       5 @      1.382 /    {2}+{3}

Select item 4 (it is redundant). Click to delete it.

Adding a new non-calculated item from the Consts library

Click the tab consts. You see a display like this:

You may see more lines than you want to read through.

Suppose you want the mass of the Moon. Type: moon into the selection string and press Enter.

• The display shrinks to just those lines with "moon" in them.

  Check the box if you want a case-sensitive selection, eg to search for A (meaning amperes) not a or A in general.

  You can search for any text, whether number, units or description.

Once you see the line you want, select it and click "Append".

• The chosen line will appear as an item at the bottom of the ttable. Click to move it up to where you want it.

The Constants library: consts

The Consts library is held in a file: uuc.ijs. To add to this file: click . The file itself contains brief instructions.

• To see your changes, restart TABULA. For a warm-start, click .

The Consts library serves both to store physical constants and to define scientific units. In order to combine both roles, every constant is given its own unique units. Thus: "mean distance; earth-moon" (defined as 3.84e8 m) is assigned "pseudo-" units [ea.moon]. When you "Append" it you will see:

plot test
  ┌ ┌  1        1.000 rad      angle
┌ │ └> 2        0.841 /        sine
├ └>   3        0.540 /        cosine
└>     4        1.382 /        sin+cos
       5        1.000 ea.moon  mean distance; earth-moon!

The new item shows the distance as "one earth-moon units", not [m] as the consts display shows.

You have a choice of ways to change the new units to familiar ones (eg to show: 3.84e8 m):

• menu: Edit > Convert to SI Units

• hotkey: Ctrl+Shift+S

• input field: enter: [m] (or: [km], [mi] etc.)

• units dropdown: select the desired units from the list of known compatible units.

The Functions library: functs

This tab lets you select from a library of calculations. It behaves like the Constants display: consts.

When you click "Append", a new calculated item is added to the ttable, PLUS all the feeder items it needs.

You can then alter the feeders' names and values, or (more commonly) you will merge each feeder with an existing item. Items for merging must be compatible, ie each convertible into the other.

The Information display: info

This serves to display various sorts of Help text:

It also lets you add a note to be saved with the ttable (called ttinfo). The note will display here when you click .

• WARNING: if you leave the Info display, say by clicking tab Ttable, you will lose what you've typed unless you first click "Update".

Contributed by IanClark

CategoryWorkInProgress