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Fix th bug where the range is not inclusive when specifying a negative number as the minimum value #14

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Merged
Eric-Butcher merged 2 commits into from
Jun 29, 2025
Merged

Fix th bug where the range is not inclusive when specifying a negative number as the minimum value #14

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84ac79d
Added test cases for inclusive ranges when generating integers
Eric-Butcher Jun 29, 2025
3340c0f
Fixed the problem with the inclusive range when engative numbers are …
Eric-Butcher Jun 29, 2025
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5 changes: 3 additions & 2 deletions src/prngs/prng.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -47,8 +47,9 @@ double PseudoRandomNumberGenerator::generateFloatingPointRandomValue(float min,

int64_t PseudoRandomNumberGenerator::generateIntegerRandomValue(int32_t min, int32_t max) {
double random_val = generateUnitNormalRandomValue();
double random_val_magnitude = random_val * (max - min + 1);
int64_t scaled_value = static_cast<int64_t>(min + random_val_magnitude);
int64_t inclusive_range = max - min + 1;
double random_val_magnitude = random_val * static_cast<double>(inclusive_range);
int64_t scaled_value = static_cast<int64_t>(random_val_magnitude) + min;
return scaled_value;
}

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52 changes: 51 additions & 1 deletion tests/test_LinearCongruentialGenerator.cpp
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Expand Up @@ -125,7 +125,7 @@ TEST(TestLinearCongruentialGenerator, GenerateIntegerRandomValueEquidistributed)
}


TEST(TestLinearCongruentialGenerator, GenerateIntegerRandomValueProducesInclusiveRange){
TEST(TestLinearCongruentialGenerator, GenerateIntegerRandomValueProducesInclusiveRangePositive){
LinearCongruentialGenerator lcg = LinearCongruentialGenerator();
const int32_t min = 1;
const int32_t max = 6;
Expand All @@ -146,6 +146,56 @@ TEST(TestLinearCongruentialGenerator, GenerateIntegerRandomValueProducesInclusiv
}
}

ASSERT_TRUE(found_min);
ASSERT_TRUE(found_max);
}

TEST(TestLinearCongruentialGenerator, GenerateIntegerRandomValueProducesInclusiveRangeNegative){
LinearCongruentialGenerator lcg = LinearCongruentialGenerator();
const int32_t min = -6;
const int32_t max = -1;
const int max_iterations = 1000;
bool found_min = false;
bool found_max = false;

for (int i = 0; i < max_iterations; ++i) {
int64_t value = lcg.generateIntegerRandomValue(min, max);
if (value == min) {
found_min = true;
}
if (value == max) {
found_max = true;
}
if (found_min && found_max) {
break; // No need to continue if both values are found
}
}

ASSERT_TRUE(found_min);
ASSERT_TRUE(found_max);
}

TEST(TestLinearCongruentialGenerator, GenerateIntegerRandomValueProducesInclusiveRangeNegativeAndPositive){
LinearCongruentialGenerator lcg = LinearCongruentialGenerator();
const int32_t min = -10;
const int32_t max = 10;
const int max_iterations = 1000;
bool found_min = false;
bool found_max = false;

for (int i = 0; i < max_iterations; ++i) {
int64_t value = lcg.generateIntegerRandomValue(min, max);
if (value == min) {
found_min = true;
}
if (value == max) {
found_max = true;
}
if (found_min && found_max) {
break; // No need to continue if both values are found
}
}

ASSERT_TRUE(found_min);
ASSERT_TRUE(found_max);
}
52 changes: 51 additions & 1 deletion tests/test_MersenneTwister.cpp
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Expand Up @@ -111,7 +111,7 @@ TEST(TestMersenneTwister, GenerateIntegerRandomValueEquidistributed){
}


TEST(TestMersenneTwister, GenerateIntegerRandomValueProducesInclusiveRange){
TEST(TestMersenneTwister, GenerateIntegerRandomValueProducesInclusiveRangePositive){
MersenneTwister mt = MersenneTwister();
const int32_t min = 1;
const int32_t max = 6;
Expand All @@ -132,6 +132,56 @@ TEST(TestMersenneTwister, GenerateIntegerRandomValueProducesInclusiveRange){
}
}

ASSERT_TRUE(found_min);
ASSERT_TRUE(found_max);
}

TEST(TestMersenneTwister, GenerateIntegerRandomValueProducesInclusiveRangeNegative){
MersenneTwister mt = MersenneTwister();
const int32_t min = -6;
const int32_t max = -1;
const int max_iterations = 1000;
bool found_min = false;
bool found_max = false;

for (int i = 0; i < max_iterations; ++i) {
int64_t value = mt.generateIntegerRandomValue(min, max);
if (value == min) {
found_min = true;
}
if (value == max) {
found_max = true;
}
if (found_min && found_max) {
break; // No need to continue if both values are found
}
}

ASSERT_TRUE(found_min);
ASSERT_TRUE(found_max);
}

TEST(TestMersenneTwister, GenerateIntegerRandomValueProducesInclusiveRangeNegativeAndPositive){
MersenneTwister mt = MersenneTwister();
const int32_t min = -10;
const int32_t max = 10;
const int max_iterations = 1000;
bool found_min = false;
bool found_max = false;

for (int i = 0; i < max_iterations; ++i) {
int64_t value = mt.generateIntegerRandomValue(min, max);
if (value == min) {
found_min = true;
}
if (value == max) {
found_max = true;
}
if (found_min && found_max) {
break; // No need to continue if both values are found
}
}

ASSERT_TRUE(found_min);
ASSERT_TRUE(found_max);
}
56 changes: 54 additions & 2 deletions tests/test_XORShift.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -123,7 +123,7 @@ TEST(TestXORShift, GenerateIntegerRandomValueEquidistributed){
ASSERT_NEAR(expected_value, average, margin_of_error);
}

TEST(TestXORShift, GenerateIntegerRandomValueProducesInclusiveRange){
TEST(TestXORShift, GenerateIntegerRandomValueProducesInclusiveRangePositive){
XORShift xor_shift = XORShift();
const int32_t min = 1;
const int32_t max = 6;
Expand All @@ -146,4 +146,56 @@ TEST(TestXORShift, GenerateIntegerRandomValueProducesInclusiveRange){

ASSERT_TRUE(found_min);
ASSERT_TRUE(found_max);
}
}

TEST(TestXORShift, GenerateIntegerRandomValueProducesInclusiveRangeNegative){
XORShift xor_shift = XORShift();
const int32_t min = -6;
const int32_t max = -1;
const int max_iterations = 1000;
bool found_min = false;
bool found_max = false;

for (int i = 0; i < max_iterations; ++i) {
int64_t value = xor_shift.generateIntegerRandomValue(min, max);
if (value == min) {
found_min = true;
}
if (value == max) {
found_max = true;
}
if (found_min && found_max) {
break; // No need to continue if both values are found
}
}

ASSERT_TRUE(found_min);
ASSERT_TRUE(found_max);
}

TEST(TestXORShift, GenerateIntegerRandomValueProducesInclusiveRangeNegativeAndPositive){
XORShift xor_shift = XORShift();
const int32_t min = -10;
const int32_t max = 10;
const int max_iterations = 1000;
bool found_min = false;
bool found_max = false;

for (int i = 0; i < max_iterations; ++i) {
int64_t value = xor_shift.generateIntegerRandomValue(min, max);
if (value == min) {
found_min = true;
}
if (value == max) {
found_max = true;
}
if (found_min && found_max) {
break; // No need to continue if both values are found
}
}

ASSERT_TRUE(found_min);
ASSERT_TRUE(found_max);
}