0.
k( 2τ )
= ( 1-k’( τ ) )/( 1+k’( τ ) )
k( τ )
= ( 1-k’( τ/2 ) )/( 1+k’( τ/2 ) )
1.
K( k( 2τ ) )
= ( ( 1+k’( τ ) )/2 )K( k( τ ) )
2.
K’( k( 2τ ) )
= ( 1+k’( τ ) )K’( k( τ ) )
3.
K( k( τ/2 ) = 2√k( τ )/( 1+k( τ ) ) )
= ( 1+k( τ ) )K( k( τ ) )