Various minor cleanup.

src/main/java/com/github/tommyettinger/anim8/OtherMath.java

@@ -149,8 +149,8 @@ private static float atanUnchecked(final float i) {
         final float c3 = c * c2;
         final float c5 = c3 * c2;
         final float c7 = c5 * c2;
-        return Math.copySign(0.7853981633974483f +
-                (0.999215f * c - 0.3211819f * c3 + 0.1462766f * c5 - 0.0389929f * c7), i);
+        return Math.signum(i) * (0.7853981633974483f +
+                (0.999215f * c - 0.3211819f * c3 + 0.1462766f * c5 - 0.0389929f * c7));
     }
 
     /**
@@ -163,7 +163,7 @@ private static float atanUnchecked(final float i) {
      * <br>
      * Credit for this goes to the 1955 research study "Approximations for Digital Computers," by RAND Corporation. This
      * is sheet 9's algorithm, which is the second-fastest and second-least precise. The algorithm on sheet 8 is faster,
-     * but only by a very small degree, and is considerably less precise. That study provides an {@link #atan(float)}
+     * but only by a very small degree, and is considerably less precise. That study provides an atan(float)
      * method, and the small code to make that work as atan2() was worked out from Wikipedia.
      * @param y y-component of the point to find the angle towards; note the parameter order is unusual by convention
      * @param x x-component of the point to find the angle towards; note the parameter order is unusual by convention

src/main/java/com/github/tommyettinger/anim8/PaletteReducer.java

@@ -61,7 +61,8 @@
  *     Neue is the default currently because it is the only dither that both handles gradients well and preserves color
  *     well. Blue Noise dither also handles gradients well, but doesn't always recognize color changes. Scatter handles
  *     color well, but can have some banding. Pattern dither usually handles gradients exceptionally well, but can have
- *     severe issues when it doesn't preserve lightness faithfully with small palettes. The list goes on.)</li>
+ *     severe issues when it doesn't preserve lightness faithfully with small palettes. The list goes on. Neue can
+ *     introduce error if the palette perfectly matches the image already; in that case, use Solid.)</li>
  *     <li>{@link #reduceKnoll(Pixmap)} (Thomas Knoll's Pattern Dithering, used more or less verbatim; this version has
  *     a heavy grid pattern that looks like an artifact. While the square grid here is a bit bad, it becomes very hard
  *     to see when the palette is large enough. This reduction is the slowest here, currently, and may noticeably delay
@@ -95,7 +96,8 @@
  *     the other algorithms take comparable amounts of time to each other, but KnollRoberts and especially Knoll are
  *     sluggish.)</li>
  *     <li>{@link #reduceSolid(Pixmap)} (No dither! Solid colors! Mostly useful when you want to preserve blocky parts
- *     of a source image, or for some kinds of pixel/low-color art.)</li>
+ *     of a source image, or for some kinds of pixel/low-color art. If you have a palette that perfectly matches the
+ *     image you are dithering, then you won't need dither, and this will be the best option.)</li>
  *     </ul>
  *     </li>
  * </ul>
@@ -257,19 +259,18 @@ public static float reverseLight(float L) {
      * would be needed.
      */
     public static final float[] TRI_BLUE_NOISE_MULTIPLIERS = ConstantData.TRI_BLUE_NOISE_MULTIPLIERS;
-    private static final double[] EXACT_LOOKUP = new double[256];
-    private static final double[] ANALYTIC_LOOKUP = new double[256];
+//    private static final double[] EXACT_LOOKUP = new double[256];
+//    private static final double[] ANALYTIC_LOOKUP = new double[256];
 
     static {
-        double r, g, b, l, m, s;
         float rf, gf, bf, lf, mf, sf;
         int idx = 0;
         for (int ri = 0; ri < 32; ri++) {
-            rf = (float) (r = ri * ri * 0.0010405827263267429); // 1.0 / 31.0 / 31.0
+            rf = (float) (ri * ri * 0.0010405827263267429); // 1.0 / 31.0 / 31.0
             for (int gi = 0; gi < 32; gi++) {
-                gf = (float) (g = gi * gi * 0.0010405827263267429); // 1.0 / 31.0 / 31.0
+                gf = (float) (gi * gi * 0.0010405827263267429); // 1.0 / 31.0 / 31.0
                 for (int bi = 0; bi < 32; bi++) {
-                    bf = (float) (b = bi * bi * 0.0010405827263267429); // 1.0 / 31.0 / 31.0
+                    bf = (float) (bi * bi * 0.0010405827263267429); // 1.0 / 31.0 / 31.0
 
                     lf = OtherMath.cbrt(0.4121656120f * rf + 0.5362752080f * gf + 0.0514575653f * bf);
                     mf = OtherMath.cbrt(0.2118591070f * rf + 0.6807189584f * gf + 0.1074065790f * bf);
@@ -285,10 +286,10 @@ public static float reverseLight(float L) {
                 }
             }
         }
-        for (int i = 1; i < 256; i++) {
-            EXACT_LOOKUP[i] = OtherMath.barronSpline(i / 255f, 4f, 0.5f);
-            ANALYTIC_LOOKUP[i] = OtherMath.barronSpline(i / 255f, 3f, 0.5f);
-        }
+//        for (int i = 1; i < 256; i++) {
+//            EXACT_LOOKUP[i] = OtherMath.barronSpline(i / 255f, 4f, 0.5f);
+//            ANALYTIC_LOOKUP[i] = OtherMath.barronSpline(i / 255f, 3f, 0.5f);
+//        }
 
 //
 //        double r, g, b, x, y, z;