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Merged
merged 7 commits into from
May 1, 2022
Merged

Add StandardDeviation.java #3039

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86b0c49
StandardDeviation.java
RaghavTaneja Apr 29, 2022
72e61e3
Merge pull request #1 from RaghavTaneja/RaghavTaneja-patch-2
RaghavTaneja Apr 29, 2022
d50869d
StandardDeviationTest.java
RaghavTaneja Apr 29, 2022
f4efb53
Merge pull request #2 from RaghavTaneja/RaghavTaneja-patch-3
RaghavTaneja Apr 29, 2022
78de356
Fixed small naming error
RaghavTaneja Apr 29, 2022
0324e6d
^
RaghavTaneja Apr 29, 2022
757b902
Fixed test case 4
RaghavTaneja Apr 29, 2022
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22 changes: 22 additions & 0 deletions src/main/java/com/thealgorithms/maths/StandardDeviation.java
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Original file line number Diff line number Diff line change
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package com.thealgorithms.maths;

public class StandardDeviation {

public static double stdDev(double[] data)
{
double var = 0;
double avg = 0;
for (int i = 0; i < data.length; i++)
{
avg += data[i];
}
avg /= data.length;
for (int j = 0; j < data.length; j++)
{
var += Math.pow((data[j] - avg), 2);
}
var /= data.length;
return Math.sqrt(var);
}

}
32 changes: 32 additions & 0 deletions src/test/java/com/thealgorithms/maths/StandardDeviationTest.java
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package com.thealgorithms.maths;

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

public class StandardDeviationTest{
@Test
void test1()
{
double[] t1 = new double[]{1,1,1,1,1};
Assertions.assertEquals(StandardDeviation.stdDev(t1), 0.0);
}
@Test
void test2()
{
double[] t2 = new double[]{1,2,3,4,5,6,7,8,9,10};
Assertions.assertEquals(StandardDeviation.stdDev(t2), 2.8722813232690143);
}
@Test
void test3()
{
double[] t3= new double[]{1.1, 8.5, 20.3, 2.4, 6.2};
Assertions.assertEquals(StandardDeviation.stdDev(t3), 6.8308125431752265);
}
@Test
void test4()
{
double[] t4 = new double[]{3.14, 2.22222, 9.89898989, 100.00045, 56.7};
Assertions.assertEquals(StandardDeviation.stdDev(t4), 38.506117353865775);
}
}