PARI/GP calculator, or **gp** for short, is an arbitrary-precision calculator (among other things) that I use frequently in my study of binary numbers. Here are instructions for installing and running it on Windows.

## Installing

- Download the PARI/GP self-installing binary distribution for Windows.
As of this writing, the current stable version is Pari-2-3-4.exe. (There’s no need to download or install the optional packages — at least I don’t need them).

- Double click on the installer file to install (install all components).

### Changing Settings

You can set gp default settings by editing the gp customization file, “\PARI\.gprc”. For example, I have edited mine as follows:

- Changed the command prompt from the default timestamp format (prompt = "(%H:%M) gp > ") to ‘?’ (
**prompt = "? "**). - Added a line (
**format = "f"**) that makes all decimals print without scientific notation.

## Running

Here are some basic things you should know about running gp:

**Starting gp**. Launch gp from the PARI folder under the Windows start menu.**Setting variables**. You can assign constants or results of calculations to variables; for example,**n=8**.**Reusing prior calculations**. The results of calculations are stored in a history array:**%1**is the result of the first calculation,**%2**is the result of the second calculation, etc. You can use these as variables in subsequent expressions.**Changing the default precision**. The default precision of printed decimal values is 28 significant digits; this can be changed with the ‘**\p**’ command. For example, ‘**\p 50**’ changes the print precision to 50 digits (PARI may set its internal precision higher than what you ask for; it must respect boundaries dictated by its implementation).**Printing decimals instead of fractions**. To force gp to print decimals instead of fractions, make sure a decimal point appears in the expression; for example,**2.^-2****Executing previous commands**. Previous commands can be accessed with the up arrow and down arrow keys.**Copying and pasting**. This is cumbersome, but can be done by right-clicking on the top of the command window and selecting ‘**edit**’. For copy, select ‘**mark**’, highlight the desired text in the command window and then hit enter. For paste, select ‘**paste**’.**Logging your session**. Type ‘**\l**’ to record your session — all commands and output — to the default PARI log file (\PARI\examples\pari.log). Type ‘**\l**’ again to stop recording.**Exiting gp**. Type ‘**quit**’ to exit gp.

## Examples

See my article “Exploring Binary Numbers With PARI/GP Calculator” for example gp calculations.

Hi Binary Man/Woman/Person,

Pari-GP sure looks good. Factorizes “small” numbers very easily. Still can’t get preloaded aliases to work. It’s supposed to just use lines like “alias(p,prime)” in the .gprc file. Here’s the response:

*** missing ‘=’: alias(p,prime)

^

…skipping line 7.

*** missing ‘=’: alias(F,fibonacci)

^

…skipping line 8.

WHAT missing “=”? The ONLY alias syntax I can find is given by the help:

07:58:27 gp > ?alias

alias(“new”,”old”): new is now an alias for old.

07:59:38 gp >

What have I forgotten?

–Bob.

@Bob,

I’ve never used ‘alias’, but I just tried it — I get the same error as you. You might want to try the PARI mailing list for help.

Binary Man (or “Doctor Binary” to you 🙂 ).

Thanks for that, Rick. I now try re-reading the .gprc file manually when running gp (\r .gprc) and then it understands aliases and user functions OK. Whew.

NOW on Windows the delete key doesn’t work. I have to cursor to the right and then backspace to erase chars. Grrr, I fall for it EVERY time, getting a ~ with a beep. Everyone looks over and says “What are you doing?”.

I saw somewhere that using a later version of cygwin1.dll may help. I have cygwin on my WIN7, but switching dlls didn’t help.

On Fedora, needless to say, the backspace AND delete keys work perfectly.

–Bob.