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Changed Math.Acos and added tests

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This commit is contained in:
Qujak 2018-01-07 20:06:02 +01:00
parent e8aa997b07
commit c31cfcef31
2 changed files with 86 additions and 3 deletions
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19
Tests/Cosmos.Compiler.Tests.Bcl/System/MathTest.cs
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@ -31,6 +31,25 @@ namespace Cosmos.Compiler.Tests.Bcl.System
#endregion Math.Asin
#region Math.Acos
result = Math.Acos(1.1);
Assert.IsTrue(double.IsNaN(result), "Math.Acos returns NaN for values larger than 1");
result = Math.Acos(-1.1);
Assert.IsTrue(double.IsNaN(result), "Math.Acos returns NaN for values smaller than -1");
result = Math.Acos(1);
Assert.IsTrue(EqualityHelper.DoublesAreEqual(result, 0), "Acos returns correct value for 1");
result = Math.Acos(-1);
Assert.IsTrue(EqualityHelper.DoublesAreEqual(result, Math.PI), "Acos returns correct value for -1");
result = Math.Acos(0);
Assert.IsTrue(EqualityHelper.DoublesAreEqual(result, 1.5707963267949), "Acos returns correct value for 9");
#endregion Math.Acos
#region Math.Cos
result = Math.Cos(4);

70
source/Cosmos.System2_Plugs/System/MathImpl.cs
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@ -67,9 +67,73 @@ namespace Cosmos.System_Plugs.System
public static double Acos(double x)
{
if ((x > 1.0) || (x < -1.0))
throw new ArgumentOutOfRangeException("Domain error");
return (pio2 - Asin(x));
double pio2_hi = 1.57079632679489655800e+00, /* 0x3FF921FB, 0x54442D18 */
pio2_lo = 6.12323399573676603587e-17, /* 0x3C91A626, 0x33145C07 */
pS0 = 1.66666666666666657415e-01, /* 0x3FC55555, 0x55555555 */
pS1 = -3.25565818622400915405e-01, /* 0xBFD4D612, 0x03EB6F7D */
pS2 = 2.01212532134862925881e-01, /* 0x3FC9C155, 0x0E884455 */
pS3 = -4.00555345006794114027e-02, /* 0xBFA48228, 0xB5688F3B */
pS4 = 7.91534994289814532176e-04, /* 0x3F49EFE0, 0x7501B288 */
pS5 = 3.47933107596021167570e-05, /* 0x3F023DE1, 0x0DFDF709 */
qS1 = -2.40339491173441421878e+00, /* 0xC0033A27, 0x1C8A2D4B */
qS2 = 2.02094576023350569471e+00, /* 0x40002AE5, 0x9C598AC8 */
qS3 = -6.88283971605453293030e-01, /* 0xBFE6066C, 0x1B8D0159 */
qS4 = 7.70381505559019352791e-02; /* 0x3FB3B8C5, 0xB12E9282 */
double z, p, q, r, w, s, c, df;
int hx, ix;
hx = HighWord(x);
ix = hx & 0x7fffffff;
if (ix >= 0x3ff00000)
{ /* |x| >= 1 */
if (((ix - 0x3ff00000) | LowWord(x)) == 0)
{ /* |x|==1 */
if (hx > 0)
return 0.0; /* acos(1) = 0 */
else
return Math.PI + 2.0 * pio2_lo; /* acos(-1)= pi */
}
return (x - x) / (x - x); /* acos(|x|>1) is NaN */
}
if (ix < 0x3fe00000)
{ /* |x| < 0.5 */
if (ix <= 0x3c600000)
return pio2_hi + pio2_lo;/*if|x|<2**-57*/
z = x * x;
p = z * (pS0 + z * (pS1 + z * (pS2 + z * (pS3 + z * (pS4 + z * pS5)))));
q = 1 + z * (qS1 + z * (qS2 + z * (qS3 + z * qS4)));
r = p / q;
return pio2_hi - (x - (pio2_lo - x * r));
}
else if (hx < 0)
{ /* x < -0.5 */
z = (1 + x) * 0.5;
p = z * (pS0 + z * (pS1 + z * (pS2 + z * (pS3 + z * (pS4 + z * pS5)))));
q = 1 + z * (qS1 + z * (qS2 + z * (qS3 + z * qS4)));
s = Math.Sqrt(z);
r = p / q;
w = r * s - pio2_lo;
return Math.PI - 2.0 * (s + w);
}
else
{ /* x > 0.5 */
z = (1 - x) * 0.5;
s = Math.Sqrt(z);
df = s;
//__LO(df) = 0;
Byte[] bdf = BitConverter.GetBytes(BitConverter.DoubleToInt64Bits(df));
for (int i = 0; i < 4; i++)
{
bdf[i + (BitConverter.IsLittleEndian ? 4 : 0)] = 0;
}
df = BitConverter.ToDouble(bdf, 0);
c = (z - df * df) / (s + df);
p = z * (pS0 + z * (pS1 + z * (pS2 + z * (pS3 + z * (pS4 + z * pS5)))));
q = 1 + z * (qS1 + z * (qS2 + z * (qS3 + z * qS4)));
r = p / q;
w = r * s + c;
return 2.0 * (df + w);
}
}
#endregion Acos