Dead code in FastMath.pow(double, double) and some improvement in test coverage
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Key: MATH-658
URL: https://issues.apache.org/jira/browse/MATH-658
Project: Commons Math
Issue Type: Improvement
Reporter: Yannick TANGUY
Priority: Minor
Fix For: 3.0
This issue concerns the FastMath class and its test class.
I don't know how to attach source code to an issue : sorry if it's not easy to
read...
(1) In the double pow(double, double) function, there are 2 identical "if"
blocks. The second one can be suppressed.
if (y < 0 && y == yi && (yi & 1) == 1) {
return Double.NEGATIVE_INFINITY;
}
// this block is never used -> to be suppressed
if (y < 0 && y == yi && (yi & 1) == 1) {
return -0.0;
}
if (y > 0 && y == yi && (yi & 1) == 1) {
return -0.0;
}
(2) To obtain better code coverage, we added some tests case in
FastMathTest.java :
/**
* Added test for log1p
*/
@Test
public void testLog1pSpecialCases() {
double x;
x = FastMath.log1p(-1.0);
if (x != Double.NEGATIVE_INFINITY)
throw new RuntimeException("Log1p of -1 should be -infinity");
}
public void testPowSpecialCases() {
// [ ... ]
// Added tests for a 100% coverage
x = FastMath.pow(Double.POSITIVE_INFINITY, Double.NaN);
if (x == x)
throw new RuntimeException("pow(+Inf, NaN) should be NaN");
x = FastMath.pow(Double.POSITIVE_INFINITY, Double.NaN);
if (x == x)
throw new RuntimeException("pow(+Inf, NaN) should be NaN");
x = FastMath.pow(1.0, Double.POSITIVE_INFINITY);
if (x == x)
throw new RuntimeException("pow(1.0, +Inf) should be NaN");
x = FastMath.pow(Double.NEGATIVE_INFINITY, Double.NaN);
if (x == x)
throw new RuntimeException("pow(-Inf, NaN) should be NaN");
x = FastMath.pow(Double.NEGATIVE_INFINITY, -1.0);
if (x != -0.0)
throw new RuntimeException("pow(-Inf, -1.0) should be 0.0");
x = FastMath.pow(Double.NEGATIVE_INFINITY, -2.0);
if (x != 0.0)
throw new RuntimeException("pow(-Inf, -2.0) should be 0.0");
x = FastMath.pow(Double.NEGATIVE_INFINITY, 1.0);
if (x != Double.NEGATIVE_INFINITY)
throw new RuntimeException("pow(-Inf, 1.0) should be -Inf");
x = FastMath.pow(Double.NEGATIVE_INFINITY, 2.0);
if (x != Double.POSITIVE_INFINITY)
throw new RuntimeException("pow(-Inf, 2.0) should be +Inf");
x = FastMath.pow(1.0, Double.NEGATIVE_INFINITY);
if (x == x)
throw new RuntimeException("pow(1.0, -Inf) should be NaN");
}
/**
* Added tests for a 100% coverage of acos().
*/
@Test
public void testAcosSpecialCases() {
double x;
x = FastMath.acos(Double.NaN);
if (x == x)
throw new RuntimeException("acos(NaN) should NaN");
x = FastMath.acos(-1.1);
if (x == x)
throw new RuntimeException("acos(-1.1) should NaN");
x = FastMath.acos(1.1);
if (x == x)
throw new RuntimeException("acos(-1.1) should NaN");
assertEquals(FastMath.acos(-1.0), FastMath.PI, Double.MIN_VALUE);
assertEquals(FastMath.acos(1.0), 0.0, Double.MIN_VALUE);
assertEquals(FastMath.acos(0.0), FastMath.PI / 2.0, Double.MIN_VALUE);
}
/**
* Added tests for a 100% coverage of asin().
*/
@Test
public void testAsinSpecialCases() {
double x;
x = FastMath.asin(Double.NaN);
if (x == x)
throw new RuntimeException("asin(NaN) should NaN");
x = FastMath.asin(-1.1);
if (x == x)
throw new RuntimeException("asin(-1.1) should NaN");
x = FastMath.asin(1.1);
if (x == x)
throw new RuntimeException("asin(-1.1) should NaN");
assertEquals(FastMath.asin(1.0), FastMath.PI / 2.0, Double.MIN_VALUE);
assertEquals(FastMath.asin(-1.0), -FastMath.PI / 2.0, Double.MIN_VALUE);
assertEquals(FastMath.asin(0.0), 0.0, Double.MIN_VALUE);
}
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