[wpimath] Replace pi with symbol in docs (#7322)

wpimath/src/main/java/edu/wpi/first/math/MathUtil.java

@@ -126,7 +126,7 @@ public final class MathUtil {
   }
 
   /**
-   * Wraps an angle to the range -pi to pi radians.
+   * Wraps an angle to the range -π to π radians.
    *
    * @param angleRadians Angle to wrap in radians.
    * @return The wrapped angle.

wpimath/src/main/java/edu/wpi/first/math/filter/LinearFilter.java

@@ -80,7 +80,7 @@ public class LinearFilter {
    * Creates a one-pole IIR low-pass filter of the form: y[n] = (1-gain) x[n] + gain y[n-1] where
    * gain = e<sup>-dt / T</sup>, T is the time constant in seconds.
    *
-   * <p>Note: T = 1 / (2 pi f) where f is the cutoff frequency in Hz, the frequency above which the
+   * <p>Note: T = 1 / (2πf) where f is the cutoff frequency in Hz, the frequency above which the
    * input starts to attenuate.
    *
    * <p>This filter is stable for time constants greater than zero.
@@ -101,7 +101,7 @@ public class LinearFilter {
    * Creates a first-order high-pass filter of the form: y[n] = gain x[n] + (-gain) x[n-1] + gain
    * y[n-1] where gain = e<sup>-dt / T</sup>, T is the time constant in seconds.
    *
-   * <p>Note: T = 1 / (2 pi f) where f is the cutoff frequency in Hz, the frequency below which the
+   * <p>Note: T = 1 / (2πf) where f is the cutoff frequency in Hz, the frequency below which the
    * input starts to attenuate.
    *
    * <p>This filter is stable for time constants greater than zero.

wpimath/src/main/java/edu/wpi/first/math/geometry/Rotation2d.java

@@ -164,7 +164,7 @@ public class Rotation2d
   }
 
   /**
-   * Adds two rotations together, with the result being bounded between -pi and pi.
+   * Adds two rotations together, with the result being bounded between -π and π.
    *
    * <p>For example, <code>Rotation2d.fromDegrees(30).plus(Rotation2d.fromDegrees(60))</code> equals
    * <code>Rotation2d(Math.PI/2.0)</code>
@@ -251,7 +251,7 @@ public class Rotation2d
    * Returns the radian value of the Rotation2d.
    *
    * @return The radian value of the Rotation2d.
-   * @see edu.wpi.first.math.MathUtil#angleModulus(double) to constrain the angle within (-pi, pi]
+   * @see edu.wpi.first.math.MathUtil#angleModulus(double) to constrain the angle within (-π, π]
    */
   @JsonProperty
   public double getRadians() {

wpimath/src/main/native/include/frc/MathUtil.h

@@ -159,7 +159,7 @@ constexpr bool IsNear(T expected, T actual, T tolerance, T min, T max) {
 }
 
 /**
- * Wraps an angle to the range -pi to pi radians (-180 to 180 degrees).
+ * Wraps an angle to the range -π to π radians (-180 to 180 degrees).
  *
  * @param angle Angle to wrap.
  */

wpimath/src/main/native/include/frc/filter/LinearFilter.h

@@ -118,7 +118,7 @@ class LinearFilter {
    *   y[n] = (1 - gain) x[n] + gain y[n-1]<br>
    * where gain = e<sup>-dt / T</sup>, T is the time constant in seconds
    *
-   * Note: T = 1 / (2 pi f) where f is the cutoff frequency in Hz, the frequency
+   * Note: T = 1 / (2πf) where f is the cutoff frequency in Hz, the frequency
    * above which the input starts to attenuate.
    *
    * This filter is stable for time constants greater than zero.
@@ -138,7 +138,7 @@ class LinearFilter {
    *   y[n] = gain x[n] + (-gain) x[n-1] + gain y[n-1]<br>
    * where gain = e<sup>-dt / T</sup>, T is the time constant in seconds
    *
-   * Note: T = 1 / (2 pi f) where f is the cutoff frequency in Hz, the frequency
+   * Note: T = 1 / (2πf) where f is the cutoff frequency in Hz, the frequency
    * below which the input starts to attenuate.
    *
    * This filter is stable for time constants greater than zero.

wpimath/src/main/native/include/frc/geometry/Rotation2d.h

@@ -67,8 +67,8 @@ class WPILIB_DLLEXPORT Rotation2d {
   }
 
   /**
-   * Adds two rotations together, with the result being bounded between -pi and
-   * pi.
+   * Adds two rotations together, with the result being bounded between -π and
+   * π.
    *
    * For example, <code>Rotation2d{30_deg} + Rotation2d{60_deg}</code> equals
    * <code>Rotation2d{units::radian_t{std::numbers::pi/2.0}}</code>
@@ -158,7 +158,7 @@ class WPILIB_DLLEXPORT Rotation2d {
    * Returns the radian value of the rotation.
    *
    * @return The radian value of the rotation.
-   * @see AngleModulus to constrain the angle within (-pi, pi]
+   * @see AngleModulus to constrain the angle within (-π, π]
    */
   constexpr units::radian_t Radians() const { return m_value; }