This indicates that random() generates fewer random bits than rand(). Right ??

Possibly not the case, validated here running non-threads, nearly 1 billion unique.

use v5.030;

use Config;
use PDL;
use Math::MPFR qw(:mpfr);
use Math::Random;
use Math::Random::MT::Auto;

say "# randbits ", $Config{randbits};
say;

{
    say "# CORE::rand()";
    CORE::srand(42);
    for (1..10) {
        my $r = CORE::rand();
        Rmpfr_dump( Math::MPFR->new($r) );
    }
    say;
}

{
    say "# PDL->random()";
    PDL::srandom(42);  # PDL::srand(42) using v2.062 ~ v2.089
    for (1..10) {
        my $r = PDL->random();
        Rmpfr_dump( Math::MPFR->new($r->at(0)) );
    }
    say;
}

{
    say "# Math::Random::random_uniform()";
    Math::Random::random_set_seed(42, 42);
    for (1..10) {
        my $r = Math::Random::random_uniform();
        Rmpfr_dump( Math::MPFR->new($r) );
    }
    say;
}

{
    say "# Math::Random::MT::Auto::rand()";
    Math::Random::MT::Auto::set_seed(42);
    for (1..10) {
        my $r = Math::Random::MT::Auto::rand();
        Rmpfr_dump( Math::MPFR->new($r) );
    }
    say;
}

[download]

Output

# randbits 48

# CORE::rand()
0.10111110100110010011000010111110010100010000000100000E0
0.10101111011101101001000101110110110001101111000000000E-1
0.11100011100000001010111000111001010100010001100000000E-3
0.11011000001111001100111111011000110001011110010000000E-1
0.10100110000111011001110100011100011010001010100000000E-3
0.11011011001111111011001010111111111011111111110000000E0
0.11111111011000101010001101001011001011001010111000000E-1
0.11110101001001110010010110001110010110100010110000000E-1
0.10110000110110010001010110010111111101100110100100000E0
0.11010101101001111110111111100010010000001100000000000E0

# PDL->random()
0.10101111101000001010000100101001111100011011001010100E-3
0.10011110111011100011111000010001111010000100001000111E-1
0.10000000001001001001010111101100010000010100010000110E-3
0.10011100111010000111111110011100100100101010011011100E-1
0.10000000100101010010000101001110111101111011110010101E-163
0.10011011001010110110000001100001001101101100010010111E-1
0.10110011011011001010101001110100111010100100100011001E-3
0.11101000011110111000100001001011101011010100100111010E-2
0.11011100111000000010100111101010011100110011111110001E0
0.10000101111100111111100010010000100100101010000110101E0

# Math::Random::random_uniform()
0.11111111111111110010000110000101111111110110110001010E0
0.11101110000010001101001101011000000100011101110001101E0
0.11000110111111000010100111101100001000110111001111100E-2
0.11111101010101011110101010101000001110110000110111100E0
0.10001101001110100011110110011001110010001010110011110E0
0.11001010101110011011001100000000100111110101000011101E0
0.11101010010000110110000001111111100100001011111000100E0
0.10001110011001110000110000110100100100000110111000100E0
0.10010010110111111100000011011111100010001001011000100E0
0.11011100010001101010110011010010010001101110111011010E-5

# Math::Random::MT::Auto::rand()
0.10000011111100001110111010101101001001100110101101010E0
0.10010000110000000011001110110001110111110111001111010E0
0.11101001010100101010111100101111111000000000110000100E0
0.11100101011001100001101111011111100011000101011101100E-1
0.11111011000000000011000100101100011111100101000000100E-1
0.10011111011111000111001111011010011100010111101000000E-2
0.10100100100000001110100110100110001110110010001100110E0
0.11101001110001010011111001011100111101111101000110010E0
0.11100100100101101001011110101000010101001011010111000E-1
0.10101100001101001001101101000011010011110011101000000E-2

[download]

In reply to Re^11: PDL and srand puzzle - not likely fewer random bits than rand by marioroy
in thread PDL and srand puzzle by syphilis

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