## To build:

``` <!---sh-->
    make
```

**NOTE**: this entry requires the `X11/Xlib.h` header file and the X11 library to
compile.  For more information see the
FAQ on "[X11](../../faq.html#X11)".


## To use:

``` <!---sh-->
    ./jarijyrki < infile.info > outfile.info
```

You will need a system capable of displaying the results of X Window programs.


## Try:

``` <!---sh-->
    ./jarijyrki < finance.sheet > myedits.info
```

Then click on cell `C3` and type in the following:

```
    C5 C6 C7 @
```

Click on cell `D4` and type in the following:

```
    C5 C6 C7 !
```

Hit `ESC`.

Now try running:

```
    ./jarijyrki < myedits.info
```

And observe that it matches what you had in the previous run!

**NOTE**: changing the dimension parameters (see the authors' remarks) renders
existing spreadsheet files unusable.


## Judges' remarks:

This entry is one of those that makes you wonder why some commercial software
needs tens to hundreds of <del>megabytes</del>gigabytes to install!  This
entry does not simply do the basics, it includes graphing features.  All this
program needs now is a [1998/banks](../../1998/banks/index.html) flight simulator!


## Author's remarks:

### 1. OVERVIEW

This program is an X-Windows based spreadsheet program.  The main functions it
supports are:

* Text cells
* Numeric cells
* Arithmetic operations: `+` `-` `*` `/`
* Pie charts
* Histograms
* Cell editing
* Formula line
* Dynamic recalculation
* Error detection
* Recursion detection
* Movement within the spreadsheet with arrow keys
* Movement within the spreadsheet with mouse
* Scrolling
* Loading and saving spreadsheets
* Visual style configuration


### 2. USAGE INSTRUCTIONS


#### 2.1. Quick Guide


##### Starting

``` <!---sh-->
    ./jarijyrki < finance.sheet > myedits.info
```


##### Stopping

Use the ESC key.


##### Movement

Click the mouse or use the arrow keys.


##### Editing

The currently selected cell is always in the edit state.  Press any key to add a
character at the end of the formula; press backspace to delete the last one.


##### Formulas

```
    123.45
    A1 A2 +
    B1 B2 -
    C1 C2 *
    D1 D2 /
```


##### Pie charts

```
    A1 A2 A3 ...
```

Finish the formula with `@` to create the pie chart.


##### Histograms

```
    A1 A2 A3 ...
```

Finish the formula with `!` to create the histogram.


#### 2.2. Starting and Loading Spreadsheets

To start the spreadsheet program with an existing
spreadsheet, for instance [finance.sheet](finance.sheet), use the following
command line:

``` <!---sh-->
    ./jarijyrki < finance.sheet
```

The file [finance.sheet](finance.sheet) has been provided as an example.  This
file contains a set of financial numbers and two graphical entities - a pie
chart and a histogram - based on them. We recommend starting the use of the
program from this file, as a way to study and learn the formula language
supported by the program.

To start the program with an empty sheet, use

``` <!---sh-->
    ./jarijyrki < /dev/null
```

Alternatively, `/dev/zero` could be used but that may not exist on all systems.


#### 2.3. Exiting and Saving Spreadsheets

Normally the user obviously wants to edit the spreadsheet.  After the
spreadsheet program finishes, it outputs the edited spreadsheet to the standard
output. Hence, when the spreadsheet window has come up, you've made your
changes, and you press the ESC key the program finishes. To save the results in
a file, the following typical command line would be used:

``` <!---sh-->
    ./jarijyrki < finance.sheet > myedits.info
```


#### 2.4. Visual Overview

On top of the window the Formula Area shows the formula (or text) of the
currently selected cell. The program starts with `A1` as being the current cell.
Below the Formula Area is the Column Letters Area: `A`, `B`, and so on.
Correspondingly, on the left side of the window is the Row Numbers Area: `1`, `2`,
and so on.  The rest of the window is dedicated to the actual spreadsheet cells.

The example spreadsheet, [finance.sheet](finance.sheet), provided with this
program contains two sets of numbers in the visible area of the spreadsheet. The
top set of numbers forms the product-by-product turnover breakdown of an
imaginary company. Below it is the yearly development of the company profits. On
the top right corner is a pie chart showing the turnover breakdown in graphical
form, and on the bottom right corner is a histogram showing the yearly
development. If you scroll the window you can see additional data from the
spreadsheet.


#### 2.5. Movement and Scrolling

Use arrow keys to move left, right, up, and down among the cells.  You may also
click the mouse on a cell to cause it to be activated as the current one.

Note that it is not possible to move around the formula; the formula can only be
edited from its end by adding or removing characters.

Going beyond the borders of the window results in scrolling the current view. It
is not possible to go up from the first row or left from the first column; but it is
possible to wrap back to start from the last row and last column.


#### 2.6. Formulas

The spreadsheet formulas operate on a stack. Operands of an operation (e.g.
plus) are first pushed to the stack and then the operation is performed. If a
formula on a cell produces *exactly* one result then that is shown in the cell.
Otherwise, the formula is interpreted as a string and shown as it is.

An example of a simple formula, simply specifying a number is

```
    123.50
```

Another simple formula refers to a cell:

```
    A1
```

This particular example formula referred to the first cell of the first row in
the spreadsheet. Arithmetic operations require both arguments:

```
    A1 A2 +
    B1 B2 *
    C1 C2 -
    D1 D2 /
```

More complex formulae can be constructed by combining these simple ones:

```
    A1 A2 + 2 *
```

This example calculates the sum of the cells `A1` and `A2`, and then multiplies
the result by two.

The currently selected cell is always in a state where it can be edited. Press
any key to add a character at the end of the formula; press backspace to delete
the last character. Any resulting recalculations are immediately visible. (Note
how much nicer this feature is as you get used to it, compared to the behaviour
of certain commercial spreadsheet programs.)


#### 2.7. Graphical Formulas

The program supports two types of graphical representations of the data in the
cells: pie charts and histograms. The pie chart can consist of any number of
slices, and is constructed by putting the pie amounts in stack and using the `@`
operator. The program automatically computes the relative size of the slices.

```
    A1 A2 A3 A4 @
```

This example would draw a pie chart of four cells, `A1` to `A4`.
The pie formula is shown above the pie for reference.

The histograms are drawn in a similar manner, by using the `!` operator:

```
    A1 A2 A3 A3 !
```


#### 2.8. Errors in Formulas

The program detects recursive reference attempts, references cells not
containing a numerical value, attempts to define formulas with zero, two, or
more results remaining on the stack, and syntax errors of formulas. Note that
typically as the user types in a formula, it toggles between valid and invalid
forms dynamically as all single character changes are immediately taken in
account. This is not dangerous, just complete the formula and view the results.

Errors are signalled by showing the formula on a cell instead of the numerical
value supposedly returned by it.

Division by zero results in an IEEE Inf number.


#### 2.9. Compilation Parameters and Configuration

This section explains the meaning and rationale for the
compile time parameters:

<hr style="width:10%;text-align:left;margin-left:0">

```
    -DC=XK_Up
    -DL=XK_Down
    -DO=XK_Left
    -DV=XK_Right
    -DR=XK_Escape
    -D_=XK_BackSpace
```

These definitions can be used to change the user interface of the program with
respect to special keys. The first four define the movement operations and
the latter two define the program termination and character deletion keys.
Typical modifications to these parameters include changing character deletion to
the key the user is most familiar with, which could also be `XK_Delete`.
`XK_Escape` might be better in some cases as one of the function keys. Likewise
for the arrow keys.


```
    -DU=40
```

This parameter defines the maximum dimensions of the stored and handled
spreadsheet (but see section 4.4 for a warning about changing this without
thinking about the consequences!).


```
    -DT=98
```

This parameter defines the maximum length of a formula in one cell. Note the
warning in section 4.4.


```
    -Dz="(T+1)*U*U"
```

Defines the number of bytes in a spreadsheet file. The number is automatically
adjusted when the spreadsheet size parameters are changed. Note the warning in
section 4.4.


```
    -DQ=80
    -DS=20
```

These two parameters define the visual dimensions of a cell.  Changing these may
be necessary on your system if the default font sizes differ from those in the
systems we've tested the program with. `S` also defines the size of the left
(`x1`) and top margins (`x2`).


```
    -DN=10
```

This is the x-indentation of text inside a cell. Changing this may be necessary
to suit other font sizes and different X environments.


```
    -DB=5
```

This is the y-indentation of text inside a cell. Changing this may be necessary
to suit other font sizes and different X environments.


```
    -DG=23
```

This parameter is the number of cell rows visible at one time.


```
    -Dp=7
```

This parameter is one smaller than the number of cells columns visible at one
time.



```
    -DM="((p+1)*Q)+S"
    -DH="(G*S)+S+S"
```

These parameters are the window x and y sizes of the spreadsheet program window.
With these definitions, they are automatically reflecting the
at-one-time-visible cell row/column amounts.  Hence, we recommend changing the
`G` and `p` parameters if you want to change the window size in normal cases.
Experimentation with `M` and `H` can be used to get other types of effect such
as adding a margin also at the bottom of the window.


### 3. IMPLEMENTATION

It's better to just read the code. But note the use of stack in the
implementation of `@` and `!` operators, and note the use of `*#i` in one of the
macros (can you see why?).  Extreme compression has been the key in writing this
program. With compression comes the use of ASCII code numbers instead of
character constants and so on. (This particular obfuscation is not really a
desirable one as it is not completely portable. But it certainly was a necessary
one.)

What does `i(=)` do or does it do anything? Why?


### 4. WARNINGS AND CAVEATS


#### 4.1. X11 Paths in Compilation

The given Makefile may have to be edited to insert correct library and include
file path names.


#### 4.2. Font Sizes

We've tested the program with a limited amount of X servers.  It is possible that
other systems use default font sizes or other parameters that cause the visual
looks to be different or perhaps even unusable; if this happens, changing
compile-time parameters explained in section 2.8 might help.


#### 4.3. Screen Sizes

The size of the window as it comes up - a parameter as defined in compile-time -
has been set suitable for a small laptop screen.  Larger screens may benefit
from setting these parameters higher.  Smaller screens require changing the
parameters so that all of the window becomes visible.


#### 4.4. Spreadsheet Dimension Changes

The size of the read, manipulated, and stored spreadsheets is defined by a
compile time parameter. However, changing this parameter is not entirely
trivial. The following constraints apply:

- Horizontal (alphabet) dimension handling will always be A to Z regardless of
the actual allocated memory area.

- Any change in the dimension parameter renders existing spreadsheet files
unusable.


#### 4.5. ASCII Reliance

The software relies on running on ASCII-based code system.  Why? Because `32` is
shorter than `' '`.


#### 4.6. Command Line Single Character Defines

The use of single character (e.g. `G` or `p`) for a `-D` option might break
certain systems, if those characters are used in the included X header files in
certain kinds of places.  If this happens, you may move the offending character
to a new name by exchanging it on the command line and in the program with
another character. Note that there are *no* free characters in the program
currently.


<!--

    Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.

    You are free to share and adapt this file under the terms of this license:

        Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)

    For more information, see:

        https://creativecommons.org/licenses/by-sa/4.0/

-->