度/秒到轴角

是否有更准确的转换方式？

除以 0.0 @ 激

当所有输入为零（甚至所有输入小于幅度）时，代码将除以 0.0。sqrt(DBL_TRUE_MIN)

在这种情况下，需要一些替代代码。

if (gyroMagnitude == 0.0) {
  // TDB code needed to handle all tiny cases.
} else {
  // The usual
}

溢出

尽管 OP 的值不太可能，但代码可能希望更好地处理溢出。在这种情况下，可以使用 TBD 替代代码或更广泛的类型。

再多看几点

是的，使用更宽的数学（当比 时更宽）和 。long doubledoubleFLT_EVAL_METHOD < 2

也许不是 OP 所寻求的几点改进，但它是：

// long double constant - degrees to radians
#defined D2R (3.1415926535897932384626433832795L / 180)

void gyroToAxisAngle(const double gyro[3], double axis_angle[4]) {
    // Convert gyro values from degrees per second to radians per second
    long double gr0 = gyro[0] * D2R;
    long double gr1 = gyro[1] * D2R;
    long double gr2 = gyro[2] * D2R;

    // Calculate the angular velocity magnitude
    long double gyroMagnitude = sqrtl(gr0*gr0 + gr1*gr1 + gr2*gr2);

    // Calculate the axis of rotation
    axis_angle[0] = (double) (gr0 / gyroMagnitude);
    axis_angle[1] = (double) (gr1 / gyroMagnitude);
    axis_angle[2] = (double) (gr2 / gyroMagnitude);

    // Calculate the rotation angle (theta)
    axis_angle[3] = (double) gyroMagnitude;
}

我估计 OP 的结果会好 1 或 2 ULP。

使用（或）打印，而不是用于评估准确性。"%.17g""%a""%f"

[编辑]

由于都是归一化的角度，因此失去了度/弧度单位，因此无需先转换为弧度。这种不必要的转换会失去一点准确性，并且是可以避免的工作。只需要度数到弧度的转换。axis_angle[0 to 2]axis_angle[3]

#include <float.h>
#include <math.h>

// Rather than  a * pi / 180, insure only 1 operation. 
#define DEGS2RADS(a) ((a) * (3.1415926535897932384626433832795/180))

void gyroToAxisAngle(const double gyro[3], double axis_angle[4]) {
  // Conversion to radians is not needed as code is forming a normalized vector.
  // Conversion slightly increases accuracy. 

  // Calculate the angular velocity magnitude
  double gyroMagnitude = sqrt(
      gyro[0] * gyro[0] + gyro[1] * gyro[1] + gyro[2] * gyro[2]);

  // See below code to handle extremes, 
  // or just handle the tiny value case with your own code
  if (gyroMagnitude == 0.0) {
    // TBD Code to handle tiny or the zero case.
    return;
  }

  axis_angle[0] = gyro[0] / gyroMagnitude;
  axis_angle[1] = gyro[1] / gyroMagnitude;
  axis_angle[2] = gyro[2] / gyroMagnitude;
  axis_angle[3] = DEGS2RADS(gyroMagnitude);
}

要处理极端情况：

  // If all the gyroRad are small, scale them up, centered about exponent = 0 
  #define SCALE (-DBL_MIN_EXP*3/4)
  if (gyroMagnitude < DBL_MIN) {
    // Scaled up versions of gyroRad_scaled[]
    double g_x[3];
    g_x[0] = scalbn(gyro[0], SCALE);
    g_x[1] = scalbn(gyro[1], SCALE);
    g_x[2] = scalbn(gyro[2], SCALE);
    gyroMagnitude = sqrt(g_x[0] * g_x[0] + g_x[1] * g_x[1] + g_x[2] * g_x[2]);
    // All gryo[] are zeros. 
    if (gyroMagnitude == 0.0) {
      // Make all same magnitude
      double mag = 1.0 / sqrt(3.0);
      axis_angle[0] = axis_angle[1] = axis_angle[2] = axis_angle[3] = 0.0;
      return;
    }
    gyroMagnitude = scalbn(gyroMagnitude, -SCALE);
  } else if (gyroMagnitude > DBL_MAX) {
    // TBD Code
    return;
  }