code: public Quaterniond fromAxisAngleRad(double axisX, double axisY, double axisZ, double angle) {
          double hangle = angle / 2.0;
          double sinAngle = Math.sin(hangle);
          double vLength = Math.sqrt(axisX * axisX + axisY * axisY + axisZ * axisZ);
          x = axisX / vLength * sinAngle;
          y = axisY / vLength * sinAngle;
          z = axisZ / vLength * sinAngle;
          w = Math.cosFromSin(sinAngle, hangle);
          return this;
      }
docs: Set this quaternion to be a representation of the supplied axis and
  angle (in radians).
  
  @param axisX
  the x component of the rotation axis
  @param axisY
  the y component of the rotation axis
  @param axisZ
  the z component of the rotation axis
  @param angle
  the angle in radians
  @return this