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A quickie. Added the Quake 3 Inverse Sqrt method.

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That_One_Nerd 2023-07-18 13:24:22 -04:00
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119
Changelog.md
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@ -1,118 +1,15 @@
# Nerd_STF v2.4.1
# Nerd_STF v2.5.0
Hey everyone! This is one of the larger small updates, and I'm pretty proud of what I got done in a week.
Along with adding setters to parts like `Float3.XY` and fixing a few bugs, almost all improvements in this update are related to matricies. First of all, I've added a bunch of new items to the `IMatrix` interface. Now, any deriving matrix has more requirements that fit the regular `Matrix` type. I don't know why one would use the `IMatrix` interface rather than a specific matrix type, but now the options are more sophisticated.
I've added some new stuff to all the matrix types, including row operations. You can now scale a row, add a row to another, and swap two rows. If I become aware of any more commonly-used row operations, I'll add then in a `2.4.2` update. But I think I've got all the good ones. There is also a mutable version of each operation which, rather than returning a new matrix with changes made, instead applies the changes to itself.
Did you know I made two seperate blunders in the `Cofactor()` method? For the `Matrix2x2` version of the `Cofactor()` method, I had the diagonal elements swapped. Whoops. For the `Matrix` version of the `Cofactor()` method, matricies with even column count would break because of the alternating sign pattern I was using. Now, as far as I know, that bug is fixed.
The last thing I did was add the ability to turn a matrix into its equivalent row-echelon form. This is applicable only to the `Matrix` type (the dynamic one), and works with some levels of success. It's a little weird and tends to give results with lots of negative zeroes, but overall it's fine, I think. As far as I know there aren't any obvious bugs. We'll see though.
Anyway, that's everything in this update. Again, pretty small, but meaningful nonetheless. Unless I haven't screwed anything up, the next update I work on will be `2.5`, so I'll see you then!
TODO:
- added better inv sqrt
Here's the full changelog:
```
* Nerd_STF
* Helpers
* UnsafeHelper
+ Q_rsqrt
* Mathematics
* Abstract
* IMatrix
+ AddRow(int, int, float)
+ AddRowMutable(int, int, float)
+ Cofactor()
+ GetColumn(int)
+ GetRow(int)
+ ScaleRow(int, float)
+ ScaleRowMutable(int, float)
+ SetColumn(int, float[])
+ SetRow(int, float[])
+ Size
+ SwapRows(int, int)
+ SwapRowsMutable(int, int)
+ this[int, int]
+ this[Index, Index]
* Algebra
* Matrix
+ AddRow(int, int, float)
+ AddRowMutable(int, int, float)
+ ScaleRow(int, float)
+ ScaleRowMutable(int, float)
+ SwapRows(int, int)
+ SwapRowsMutable(int, int)
= Fixed a blunder in `SignGrid(Int2)` with signs being incorrectly placed on matrixes with even column count.
* Matrix2x2
+ AddRow(int, int, float)
+ AddRowMutable(int, int, float)
+ GetColumn(int)
+ GetRow(int)
+ ScaleRow(int, float)
+ ScaleRowMutable(int, float)
+ SetColumn(int, float[])
+ SetRow(int, float[])
+ Size
+ SwapRows(int, int)
+ SwapRowsMutable(int, int)
= Fixed a blunder in `Cofactor()` with the position of elements.
* Matrix3x3
+ AddRow(int, int, float)
+ AddRowMutable(int, int, float)
+ GetColumn(int)
+ GetRow(int)
+ ScaleRow(int, float)
+ ScaleRowMutable(int, float)
+ SetColumn(int, float[])
+ SetRow(int, float[])
+ Size
+ SwapRows(int, int)
+ SwapRowsMutable(int, int)
* Matrix4x4
+ AddRow(int, int, float)
+ AddRowMutable(int, int, float)
+ GetColumn(int)
+ GetRow(int)
+ ScaleRow(int, float)
+ ScaleRowMutable(int, float)
+ SetColumn(int, float[])
+ SetRow(int, float[])
+ Size
+ SwapRows(int, int)
+ SwapRowsMutable(int, int)
* NumberSystems
* Complex
+ operator Complex(SystemComplex)
+ operator SystemComplex(Complex)
* Quaternion
+ operator Quaternion(SystemQuaternion)
+ operator SystemQuaternion(Quaternion)
* Float3
= Added a setter to `XY`
= Added a setter to `XZ`
= Added a setter to `YZ`
* Float4
= Added a setter to `XW`
= Added a setter to `XY`
= Added a setter to `XZ`
= Added a setter to `YW`
= Added a setter to `YZ`
= Added a setter to `ZW`
= Added a setter to `XYW`
= Added a setter to `XYZ`
= Added a setter to `XZW`
= Added a setter to `YZW`
* Int3
= Added a setter to `XY`
= Added a setter to `XZ`
= Added a setter to `YZ`
* Int4
= Added a setter to `XW`
= Added a setter to `XY`
= Added a setter to `XZ`
= Added a setter to `YW`
= Added a setter to `YZ`
= Added a setter to `ZW`
= Added a setter to `XYW`
= Added a setter to `XYZ`
= Added a setter to `XZW`
= Added a setter to `YZW`
* Mathf
= Modified `InverseSqrt(float)` to use the faster unsafe inverse square root method.
```

19
Nerd_STF/Helpers/UnsafeHelper.cs
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@ -10,4 +10,23 @@ internal static unsafe class UnsafeHelper
where CT : unmanaged
where NT : unmanaged
=> *(NT*)&obj;
// Fast square root thing. Uses the classic Quake 3 algorithm.
// I'll be preserving variable names and comments for funzies.
public static float Q_rsqrt(float number)
{
int i;
float x2, y;
const float threehalfs = 1.5F;
x2 = number * 0.5F;
y = number;
i = * ( int * ) &y; // evil floating point bit hack
i = 0x5f3759df - ( i >> 1 ); // what the fuck?
y = * ( float * ) &i;
y = y * ( threehalfs - ( x2 * y * y ) ); // 1st iteration
// y = y * ( threehalfs - ( x2 * y * y ) ); // 2nd iteration, can be removed.
return y;
}
}

2
Nerd_STF/Mathematics/Mathf.cs
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@ -155,7 +155,7 @@ public static class Mathf
return -1;
}
public static float InverseSqrt(float val) => 1 / Sqrt(val);
public static float InverseSqrt(float val) => UnsafeHelper.Q_rsqrt(val);
public static bool IsPrime(int num, PrimeCheckMethod method = PrimeCheckMethod.Classic) =>
method switch