chord()

Point at distance h from I in the plane IJK forming a right angle between I and J on the opposite side of IJ from K.

It's called a chord because by definition, the three points (two joint centres and the joint marker) lie on the periphery of a circle.

This function is useful in locating the center of the knee joint given the hip joint center and a marker on the mid-thigh and lateral condyle of the knee: I is set to the lateral knee marker position, J to the hip joint center position, and K to the position of the mid-thigh marker. This is a re-implemementation of the equal named function used in Vicon Clinical manager gait analysis software.

Argument and result types

argument name Description type
1 
h
 
double
2 
I
 
3d vector
3 
J
 
3d vector
4 
K
 
3d vector
5 
a
 
double
result value 

      		
      
      
      
3d vector

      		
    

  




Examples






chord(h,I,J,K)