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Function Reference: @lti/lft

Function File: sys = lft (sys1, sys2)
Function File: sys = lft (sys1, sys2, nu, ny)

Linear fractional tranformation, also known as Redheffer star product.

Inputs

sys1
Upper LTI model.
sys2
Lower LTI model.
nu
The last nu inputs of sys1 are connected with the first nu outputs of sys2. If not specified, min (m1, p2) is taken.
ny
The last ny outputs of sys1 are connected with the first ny inputs of sys2. If not specified, min (p1, m2) is taken.

Outputs

sys
Resulting LTI model.

Block Diagram

 
       .............sys..............
       :         +--------+         :
 w1 ------------>|        |------------> z1
       :         |  sys1  |         :
       : u +---->|        |-----+ y :
       :   |     +--------+     |   :          Lower LFT
       :   |                    |   :
       :   |     +--------+     |   :          lft (sys1, sys2)
       :   +-----|  sys2  |<----+   :
       :         +--------+         :
       :............................:
 
       .............sys..............
       :         +--------+         :
       : u +---->|  sys1  |-----+ y :
       :   |     +--------+     |   :          Upper LFT
       :   |                    |   :
       :   |     +--------+     |   :          lft (sys1, sys2)
       :   +-----|        |<----+   :
       :         |  sys2  |         :
 z2 <------------|        |<------------ w2
       :         +--------+         :
       :............................:
 
       .............sys..............
       :         +--------+         :
 w1 ------------>|        |------------> z1
       :         |  sys1  |         :
       : u +---->|        |-----+ y :
       :   |     +--------+     |   :
       :   |                    |   :          lft (sys1, sys2, nu, ny)
       :   |     +--------+     |   :
       :   +-----|        |<----+   :
       :         |  sys2  |         :
 z2 <------------|        |<------------ w2
       :         +--------+         :
       :............................:

Source Code: @lti/lft