Brute force CRT.

diff --git a/src/main/java/frc/robot/util/Remainders.java b/src/main/java/frc/robot/util/Remainders.java
new file mode 100644 (file)
index 0000000..0086c8d
--- /dev/null
+++ b/src/main/java/frc/robot/util/Remainders.java
@@ -0,0 +1,25 @@
+package frc.robot.util;
+
+public class Remainders {
+       public record Encoder(double val, double mod) {
+       }
+
+       public static double compute(Encoder a, Encoder b, double tolerance) {
+               double testing = a.val();
+               while (true) {
+                       if (Math.abs(testing % a.mod() - a.val()) <= tolerance &&
+                                       Math.abs(testing % b.mod() - b.val()) <= tolerance)
+                               return testing;
+
+                       // alternately check positive and negative
+                       if (testing > a.val()) {
+                               double diff = testing - a.val();
+                               testing -= 2 * diff;
+                       } else {
+                               double diff = a.val() - testing;
+                               testing += 2 * diff;
+                               testing += a.mod();
+                       }
+               }
+       }
+}

diff --git a/src/test/java/frc/robot/util/RemainderTest.java b/src/test/java/frc/robot/util/RemainderTest.java
new file mode 100644 (file)
index 0000000..52cbf01
--- /dev/null
+++ b/src/test/java/frc/robot/util/RemainderTest.java
@@ -0,0 +1,31 @@
+
+package frc.robot.util;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import frc.robot.util.Remainders.Encoder;
+
+public class RemainderTest {
+
+       @BeforeEach
+       public void prepare() {
+       }
+
+       @AfterEach
+       public void cleanup() {
+       }
+
+       @Test
+       public void test() {
+               double tolerance = 0.01;
+
+               Encoder a = new Encoder(5000 % 123, 123);
+               Encoder b = new Encoder(5000 % 321, 321);
+               double val = Remainders.compute(a, b, tolerance);
+               assertEquals(5000, val, tolerance);
+       }
+}