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// SPDX-License-Identifier: GPL-2.0
#include <kunit/test.h>
#include "mean_and_variance.h"
#define MAX_SQR (SQRT_U64_MAX*SQRT_U64_MAX)
static void mean_and_variance_basic_test(struct kunit *test)
{
struct mean_and_variance s = {};
mean_and_variance_update(&s, 2);
mean_and_variance_update(&s, 2);
KUNIT_EXPECT_EQ(test, mean_and_variance_get_mean(s), 2);
KUNIT_EXPECT_EQ(test, mean_and_variance_get_variance(s), 0);
KUNIT_EXPECT_EQ(test, s.n, 2);
mean_and_variance_update(&s, 4);
mean_and_variance_update(&s, 4);
KUNIT_EXPECT_EQ(test, mean_and_variance_get_mean(s), 3);
KUNIT_EXPECT_EQ(test, mean_and_variance_get_variance(s), 1);
KUNIT_EXPECT_EQ(test, s.n, 4);
}
/*
* Test values computed using a spreadsheet from the psuedocode at the bottom:
* https://fanf2.user.srcf.net/hermes/doc/antiforgery/stats.pdf
*/
static void mean_and_variance_weighted_test(struct kunit *test)
{
struct mean_and_variance_weighted s = { .weight = 2 };
mean_and_variance_weighted_update(&s, 10);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), 10);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 0);
mean_and_variance_weighted_update(&s, 20);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), 12);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 18);
mean_and_variance_weighted_update(&s, 30);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), 16);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 72);
s = (struct mean_and_variance_weighted) { .weight = 2 };
mean_and_variance_weighted_update(&s, -10);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), -10);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 0);
mean_and_variance_weighted_update(&s, -20);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), -12);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 18);
mean_and_variance_weighted_update(&s, -30);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), -16);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 72);
}
static void mean_and_variance_weighted_advanced_test(struct kunit *test)
{
struct mean_and_variance_weighted s = { .weight = 8 };
s64 i;
for (i = 10; i <= 100; i += 10)
mean_and_variance_weighted_update(&s, i);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), 11);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 107);
s = (struct mean_and_variance_weighted) { .weight = 8 };
for (i = -10; i >= -100; i -= 10)
mean_and_variance_weighted_update(&s, i);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(s), -11);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_variance(s), 107);
}
static void do_mean_and_variance_test(struct kunit *test,
s64 initial_value,
s64 initial_n,
s64 n,
unsigned weight,
s64 *data,
s64 *mean,
s64 *stddev,
s64 *weighted_mean,
s64 *weighted_stddev)
{
struct mean_and_variance mv = {};
struct mean_and_variance_weighted vw = { .weight = weight };
for (unsigned i = 0; i < initial_n; i++) {
mean_and_variance_update(&mv, initial_value);
mean_and_variance_weighted_update(&vw, initial_value);
KUNIT_EXPECT_EQ(test, mean_and_variance_get_mean(mv), initial_value);
KUNIT_EXPECT_EQ(test, mean_and_variance_get_stddev(mv), 0);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(vw), initial_value);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_stddev(vw),0);
}
for (unsigned i = 0; i < n; i++) {
mean_and_variance_update(&mv, data[i]);
mean_and_variance_weighted_update(&vw, data[i]);
KUNIT_EXPECT_EQ(test, mean_and_variance_get_mean(mv), mean[i]);
KUNIT_EXPECT_EQ(test, mean_and_variance_get_stddev(mv), stddev[i]);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_mean(vw), weighted_mean[i]);
KUNIT_EXPECT_EQ(test, mean_and_variance_weighted_get_stddev(vw),weighted_stddev[i]);
}
KUNIT_EXPECT_EQ(test, mv.n, initial_n + n);
}
/* Test behaviour with a single outlier, then back to steady state: */
static void mean_and_variance_test_1(struct kunit *test)
{
s64 d[] = { 100, 10, 10, 10, 10, 10, 10 };
s64 mean[] = { 22, 21, 20, 19, 18, 17, 16 };
s64 stddev[] = { 32, 29, 28, 27, 26, 25, 24 };
s64 weighted_mean[] = { 32, 27, 22, 19, 17, 15, 14 };
s64 weighted_stddev[] = { 38, 35, 31, 27, 24, 21, 18 };
do_mean_and_variance_test(test, 10, 6, ARRAY_SIZE(d), 2,
d, mean, stddev, weighted_mean, weighted_stddev);
}
/* Test behaviour where we switch from one steady state to another: */
static void mean_and_variance_test_2(struct kunit *test)
{
s64 d[] = { 100, 100, 100, 100, 100 };
s64 mean[] = { 22, 32, 40, 46, 50 };
s64 stddev[] = { 32, 39, 42, 44, 45 };
s64 weighted_mean[] = { 32, 49, 61, 71, 78 };
s64 weighted_stddev[] = { 38, 44, 44, 41, 38 };
do_mean_and_variance_test(test, 10, 6, ARRAY_SIZE(d), 2,
d, mean, stddev, weighted_mean, weighted_stddev);
}
static void mean_and_variance_fast_divpow2(struct kunit *test)
{
s64 i;
u8 d;
for (i = 0; i < 100; i++) {
d = 0;
KUNIT_EXPECT_EQ(test, fast_divpow2(i, d), div_u64(i, 1LLU << d));
KUNIT_EXPECT_EQ(test, abs(fast_divpow2(-i, d)), div_u64(i, 1LLU << d));
for (d = 1; d < 32; d++) {
KUNIT_EXPECT_EQ_MSG(test, abs(fast_divpow2(i, d)),
div_u64(i, 1 << d), "%lld %u", i, d);
KUNIT_EXPECT_EQ_MSG(test, abs(fast_divpow2(-i, d)),
div_u64(i, 1 << d), "%lld %u", -i, d);
}
}
}
static void mean_and_variance_u128_basic_test(struct kunit *test)
{
u128_u a = u64s_to_u128(0, U64_MAX);
u128_u a1 = u64s_to_u128(0, 1);
u128_u b = u64s_to_u128(1, 0);
u128_u c = u64s_to_u128(0, 1LLU << 63);
u128_u c2 = u64s_to_u128(U64_MAX, U64_MAX);
KUNIT_EXPECT_EQ(test, u128_hi(u128_add(a, a1)), 1);
KUNIT_EXPECT_EQ(test, u128_lo(u128_add(a, a1)), 0);
KUNIT_EXPECT_EQ(test, u128_hi(u128_add(a1, a)), 1);
KUNIT_EXPECT_EQ(test, u128_lo(u128_add(a1, a)), 0);
KUNIT_EXPECT_EQ(test, u128_lo(u128_sub(b, a1)), U64_MAX);
KUNIT_EXPECT_EQ(test, u128_hi(u128_sub(b, a1)), 0);
KUNIT_EXPECT_EQ(test, u128_hi(u128_shl(c, 1)), 1);
KUNIT_EXPECT_EQ(test, u128_lo(u128_shl(c, 1)), 0);
KUNIT_EXPECT_EQ(test, u128_hi(u128_square(U64_MAX)), U64_MAX - 1);
KUNIT_EXPECT_EQ(test, u128_lo(u128_square(U64_MAX)), 1);
KUNIT_EXPECT_EQ(test, u128_lo(u128_div(b, 2)), 1LLU << 63);
KUNIT_EXPECT_EQ(test, u128_hi(u128_div(c2, 2)), U64_MAX >> 1);
KUNIT_EXPECT_EQ(test, u128_lo(u128_div(c2, 2)), U64_MAX);
KUNIT_EXPECT_EQ(test, u128_hi(u128_div(u128_shl(u64_to_u128(U64_MAX), 32), 2)), U32_MAX >> 1);
KUNIT_EXPECT_EQ(test, u128_lo(u128_div(u128_shl(u64_to_u128(U64_MAX), 32), 2)), U64_MAX << 31);
}
static struct kunit_case mean_and_variance_test_cases[] = {
KUNIT_CASE(mean_and_variance_fast_divpow2),
KUNIT_CASE(mean_and_variance_u128_basic_test),
KUNIT_CASE(mean_and_variance_basic_test),
KUNIT_CASE(mean_and_variance_weighted_test),
KUNIT_CASE(mean_and_variance_weighted_advanced_test),
KUNIT_CASE(mean_and_variance_test_1),
KUNIT_CASE(mean_and_variance_test_2),
{}
};
static struct kunit_suite mean_and_variance_test_suite = {
.name = "mean and variance tests",
.test_cases = mean_and_variance_test_cases
};
kunit_test_suite(mean_and_variance_test_suite);
MODULE_AUTHOR("Daniel B. Hill");
MODULE_LICENSE("GPL");
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