Sometimes you just need a pseudo-random number. Useful for sampling vertices from a graph or if you write data generators in GSQL.

So, these days I have a UDF for this, but sometimes you don’t have that available, and you need a random number. For this I have a small generator. These aren’t particularly good random numbers, but for basic work they seem to be okay.

Here is the routine. Note you feed it with a floating point number between 0 and 1. No doubt there are better generators, but for that I use a UDF.

Here it is:

```
CREATE QUERY myRand(FLOAT prev_rand) FOR GRAPH MyGraph RETURNS (FLOAT) {
// Cliff's number generator
// This is NOT cryptographically secure
// As it has no entropy, and is entirely predictable
FLOAT rand_out;
IF prev_rand<0.000001 THEN // zero test without a warning
rand_out = 0.1; // Cliff's standard starting value
ELSE
rand_out=prev_rand;
END;
rand_out = 100*log(rand_out);
rand_out = abs(rand_out);
rand_out = rand_out - floor(rand_out);
PRINT rand_out; // only prints when run standalone i.e. debug
RETURN rand_out;
}
```