ss2sos

(/tools/hpmatlab/toolbox/signal/ss2sos.m)

Function Synopsis

sos = ss2sos(a,b,c,d,IU,direction_flag)

Help text

SS2SOS	State-space to second-order sections linear system model conversion
	SOS = SS2SOS(A,B,C,D) finds a matrix SOS in second-order sections form
	which represents the same system as the one with single-input, 
	single-output state space matrices A, B, C, and D.  The zeros and 
	poles of the system A, B, C, D must be in complex conjugate pairs.

	SOS = SS2SOS(A,B,C,D,IU) uses the IUth input of the multi-input, single-
	output state space matrices A, B, C and D.
 
	SS2SOS(A,B,C,D,'down') and SS2SOS(A,B,C,D,IU,'down') order the sections
	so that the first row of SOS contains the poles closest to the unit 
	circle.  Without the 'down' flag, the sections are ordered in the other
	direction.

	The output SOS is an L by 6 matrix which contains the coefficients 
	of each second-order section in its rows:
	    SOS = [ b01 b11 b21  a01 a11 a21 
	            b02 b12 b22  a02 a12 a22
	            ...
	            b0L b1L b2L  a0L a1L a2L ]
	The pole-zero conjugate pairs which are closest to each other are 
	arranged into the same 2nd-order section.  Furthermore, the numerator
	coefficients of each section are scaled so that the maximum of the
	magnitude of the DTFT of the cascade is very close to 1.

	The system transfer function is the product of the second-order transfer
	functions of the sections.  Each row of the SOS matrix describes
	a 2nd order transfer function as
	        b0k +  b1k z^-1 +  b2k  z^-2
	        ----------------------------
	        a0k +  a1k z^-1 +  a2k  z^-2
	where k is the row index.

	See also SOS2SS, ZP2SOS, SOS2TF, SOS2ZP, CPLXPAIR.

Cross-Reference Information

else           /tools/hpmatlab/toolbox/matlab/lang/else.m
elseif         /tools/hpmatlab/toolbox/matlab/lang/elseif.m
end            /tools/hpmatlab/toolbox/matlab/lang/end.m
error          /tools/hpmatlab/toolbox/matlab/lang/error.m
if             /tools/hpmatlab/toolbox/matlab/lang/if.m
input          /tools/hpmatlab/toolbox/matlab/lang/input.m
nargchk        /tools/hpmatlab/toolbox/matlab/lang/nargchk.m
nargin         /tools/hpmatlab/toolbox/matlab/elmat/nargin.m
size           /tools/hpmatlab/toolbox/matlab/general/size.m
ss2zp          /tools/hpmatlab/toolbox/signal/ss2zp.m
zp2sos         /tools/hpmatlab/toolbox/signal/zp2sos.m