Data from extensive computations on class groups of quadratic imaginary fields is available below. It is organized by fundamental discriminant $-d$, and divided into four groups based on congruences:

For each congruence class above, there are 4096 files, indexed from $k=0$ to $k=4095$. The $k$th file contains data for $k\cdot 2^{28} \leq |d| \lt (k+1)\cdot 2^{28}$. The files are named accordingly, so the $k=12$th file for $d\equiv 7\pmod8$ is called cl7mod8.12.gz, the final extension because it has been compressed with gzip. The compressed files range in size from 50 to 200 megabytes.

File and data format

The $k$th file of data for $d\equiv r\pmod{m}$ has filename of the form cl{$r$}mod{$m$}.{$k$} after uncompressing with gzip (for example, file $12$ for $d\equiv7\pmod8$ is cl7mod8.12). In this file there is one line per discriminant, with discriminants in order of their absolute value. The discriminants and associated class group data may be extracted as follows, where for $i\ge1$ we define $-d_i$ to be the $i$th discriminant of the file:

For example, the first two lines of file cl4mod16.1 are

$0$ $12160$ $380\ 4\ 4\ 2$
$2$ $4392$ $2196\ 2$
so and so on.

File download

$d \equiv $
$k = $ integer from 0 to 4095