rand: reorganize: phase 2

vlib/rand/mt19937/mt19937_test.v

@@ -0,0 +1,341 @@
+import mt19937
+import math
+import rand.util
+
+const (
+	range_limit = 40
+	value_count = 1000
+	seeds       = [[u32(0xcafebabe), u32(0xdeadbeef)], [u32(0xc0de), u32(0xfeed)]]
+)
+
+const (
+	sample_size   = 1000
+	stats_epsilon = 0.05
+	inv_sqrt_12   = 1.0 / math.sqrt(12)
+)
+
+fn mt19937_basic_test() {
+	mut rng := mt19937.MT19937RNG{}
+	rng.seed([u32(0xdeadbeef)])
+	target := [956529277, 3842322136, 3319553134, 1843186657, 2704993644, 595827513, 938518626,
+		1676224337, 3221315650, 1819026461]
+	for i := 0; i < 10; i++ {
+		assert target[i] == rng.u32()
+	}
+}
+
+fn gen_randoms(seed_data []u32, bound int) []u64 {
+	bound_u64 := u64(bound)
+	mut randoms := [u64(0)].repeat(20)
+	mut rnd := mt19937.MT19937RNG{}
+	rnd.seed(seed_data)
+	for i in 0 .. 20 {
+		randoms[i] = rnd.u64n(bound_u64)
+	}
+	return randoms
+}
+
+fn test_mt19937_reproducibility() {
+	seed_data := util.time_seed_array(2)
+	randoms1 := gen_randoms(seed_data, 1000)
+	randoms2 := gen_randoms(seed_data, 1000)
+	assert randoms1.len == randoms2.len
+	len := randoms1.len
+	for i in 0 .. len {
+		assert randoms1[i] == randoms2[i]
+	}
+}
+
+// TODO: use the `in` syntax and remove this function
+// after generics has been completely implemented
+fn found(value u64, arr []u64) bool {
+	for item in arr {
+		if value == item {
+			return true
+		}
+	}
+	return false
+}
+
+fn test_mt19937_variability() {
+	// If this test fails and if it is certainly not the implementation
+	// at fault, try changing the seed values. Repeated values are
+	// improbable but not impossible.
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		mut values := []u64{cap: value_count}
+		for i in 0 .. value_count {
+			value := rng.u64()
+			assert !found(value, values)
+			assert values.len == i
+			values << value
+		}
+	}
+}
+
+fn check_uniformity_u64(mut rng mt19937.MT19937RNG, range u64) {
+	range_f64 := f64(range)
+	expected_mean := range_f64 / 2.0
+	mut variance := 0.0
+	for _ in 0 .. sample_size {
+		diff := f64(rng.u64n(range)) - expected_mean
+		variance += diff * diff
+	}
+	variance /= sample_size - 1
+	sigma := math.sqrt(variance)
+	expected_sigma := range_f64 * inv_sqrt_12
+	error := (sigma - expected_sigma) / expected_sigma
+	assert math.abs(error) < stats_epsilon
+}
+
+fn test_mt19937_uniformity_u64() {
+	ranges := [14019545, 80240, 130]
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for range in ranges {
+			check_uniformity_u64(mut rng, u64(range))
+		}
+	}
+}
+
+fn check_uniformity_f64(mut rng mt19937.MT19937RNG) {
+	expected_mean := 0.5
+	mut variance := 0.0
+	for _ in 0 .. sample_size {
+		diff := rng.f64() - expected_mean
+		variance += diff * diff
+	}
+	variance /= sample_size - 1
+	sigma := math.sqrt(variance)
+	expected_sigma := inv_sqrt_12
+	error := (sigma - expected_sigma) / expected_sigma
+	assert math.abs(error) < stats_epsilon
+}
+
+fn test_mt19937_uniformity_f64() {
+	// The f64 version
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		check_uniformity_f64(mut rng)
+	}
+}
+
+fn test_mt19937_u32n() {
+	max := u32(16384)
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.u32n(max)
+			assert value >= 0
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_u64n() {
+	max := u64(379091181005)
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.u64n(max)
+			assert value >= 0
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_u32_in_range() {
+	max := u32(484468466)
+	min := u32(316846)
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.u32_in_range(min, max)
+			assert value >= min
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_u64_in_range() {
+	max := u64(216468454685163)
+	min := u64(6848646868)
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.u64_in_range(min, max)
+			assert value >= min
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_int31() {
+	max_u31 := 0x7FFFFFFF
+	sign_mask := 0x80000000
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.int31()
+			assert value >= 0
+			assert value <= max_u31
+			// This statement ensures that the sign bit is zero
+			assert (value & sign_mask) == 0
+		}
+	}
+}
+
+fn test_mt19937_int63() {
+	max_u63 := i64(0x7FFFFFFFFFFFFFFF)
+	sign_mask := i64(0x8000000000000000)
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.int63()
+			assert value >= 0
+			assert value <= max_u63
+			assert (value & sign_mask) == 0
+		}
+	}
+}
+
+fn test_mt19937_intn() {
+	max := 2525642
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.intn(max)
+			assert value >= 0
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_i64n() {
+	max := i64(3246727724653636)
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.i64n(max)
+			assert value >= 0
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_int_in_range() {
+	min := -4252
+	max := 1034
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.int_in_range(min, max)
+			assert value >= min
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_i64_in_range() {
+	min := i64(-24095)
+	max := i64(324058)
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.i64_in_range(min, max)
+			assert value >= min
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_f32() {
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.f32()
+			assert value >= 0.0
+			assert value < 1.0
+		}
+	}
+}
+
+fn test_mt19937_f64() {
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.f64()
+			assert value >= 0.0
+			assert value < 1.0
+		}
+	}
+}
+
+fn test_mt19937_f32n() {
+	max := f32(357.0)
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.f32n(max)
+			assert value >= 0.0
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_f64n() {
+	max := 1.52e6
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.f64n(max)
+			assert value >= 0.0
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_f32_in_range() {
+	min := f32(-24.0)
+	max := f32(125.0)
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.f32_in_range(min, max)
+			assert value >= min
+			assert value < max
+		}
+	}
+}
+
+fn test_mt19937_f64_in_range() {
+	min := -548.7
+	max := 5015.2
+	for seed in seeds {
+		mut rng := mt19937.MT19937RNG{}
+		rng.seed(seed)
+		for _ in 0 .. range_limit {
+			value := rng.f64_in_range(min, max)
+			assert value >= min
+			assert value < max
+		}
+	}
+}