rand: add random functions for f32 and f64, [0,max] and [min,max] versions

vlib/rand/rand.v

@@ -23,3 +23,25 @@ pub fn rand_r(seed &int) int {
 	}
 	return ns & 0x7fffffff
 }
+
+// rand_f32 return a random f32 between 0 and max
+pub fn rand_f32(max f32) f32 {
+    return f32( f64(C.rand()) / ( f64(C.RAND_MAX)/f64(max) ) )
+}
+
+// rand_f32 return a random f32 in range min and max
+pub fn rand_f32_in_range(min f32, max f32) f32 {
+    scaled_r := f32(rand.next( 2147483647 )) / 2147483647.0
+    return min + scaled_r * (max - min )
+}
+
+// rand_f64 return a random f64 between 0 and max
+pub fn rand_f64(max f32) f32 {
+    return f64(C.rand()) / ( f64(C.RAND_MAX)/f64(max) )
+}
+
+// rand_f64 return a random f64 in range min and max
+pub fn rand_f64_in_range(min f64, max f64) f64 {
+    scaled_r := f64(rand.next( 2147483647 )) / 2147483647.0
+    return min + scaled_r * (max - min )
+}

vlib/rand/random_numbers_test.v

@@ -56,3 +56,50 @@ fn assert_randoms_equal(r1, r2 []int) {
 		assert r1[i] == r2[i]
 	}
 }
+
+fn test_rand_f32() {
+
+	mut prev_res := f32(-1.0)
+	for _ in 0..rnd_count+1 {
+		res := rand.rand_f32(1.0)
+
+		assert res >= 0.0
+		assert res <= 1.0
+
+		prev_res = res
+	}
+}
+
+
+fn test_rand_f32_in_range() {
+
+	for _ in 0..rnd_count+1 {
+		res := rand.rand_f32_in_range(1.0,2.0)
+
+		assert res >= 1.0
+		assert res <= 2.0
+
+		// NOTE assert res != prev_res
+		// ^- this kind of test can and WILL fail. Random numbers can be the same in subsequent runs
+	}
+}
+
+fn test_rand_f64() {
+
+	for _ in 0..rnd_count+1 {
+		res := rand.rand_f64(1.0)
+
+		assert res >= 0.0
+		assert res <= 1.0
+	}
+}
+
+fn test_rand_f64_in_range() {
+
+	for _ in 0..rnd_count {
+		res := rand.rand_f64_in_range(1.0,2.0)
+
+		assert res >= 1.0
+		assert res <= 2.0
+	}
+}