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randomprecisionmaxima

How to compute random bfloat number in Maxima CAS

Maxima Cas random function takes as an input floating point number and gives floating point number as an output.

I need floating point number with more digits, so I use bfloat with increased precision.

I have tried : 

random(1.0b0)
bfloat(random(1.0));

The best result was :

bfloat(%pi)/6.000000000000000000000000000000000000000000b0 5.235987755982988730771072305465838140328615665625176368291574320513027343810348331046724708903528447b-1

but it is not random.

Solution

  • One way to generate a random bigfloat is to generate an integer with the appropriate number of bits and then rescale it to get a number in the range 0 to 1.

    Note that random(n) returns an integer in the range 0 to n - 1 when n is an integer, therefore: bfloat(random(10^fpprec) / 10^fpprec).