What's the difference between getEulerYPR, getEulerZYX and getRPY?

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Hello everyone, I noticed tf::Matrix3x3 provides 3 distinct methods (getEulerYPR, getEulerZYX and getRPY) and they all seem to give the very same results :

The output of the following snippet is given below :

   double roll, pitch, yaw;
   tf::Matrix3x3(transform.getRotation()).getRPY(roll, pitch, yaw);

   std::cout<<"getRPY():      "<<roll<<" "<<pitch<<" "<<yaw<<"\n";
   tf::Matrix3x3(transform.getRotation()).getEulerYPR(yaw, pitch, roll);
   std::cout<<"getEulerYPR(): "<<roll<<" "<<pitch<<" "<<yaw<<"\n";
   tf::Matrix3x3(transform.getRotation()).getEulerZYX(yaw, pitch, roll);
   std::cout<<"getEulerZYX(): "<<roll<<" "<<pitch<<" "<<yaw<<"\n";

outputs:

getRPY():      0.000254904 -0.00770209 -0.0312527
getEulerYPR(): 0.000254904 -0.00770209 -0.0312527
getEulerZYX(): 0.000254904 -0.00770209 -0.0312527

Why do we have duplicate methods that seem to do exactly one thing? Can somebody please shed some light on this? Thanks a lot in advance