getiv, sortiv, tackon (Mu Analysis and Synthesis Toolbox)

Mu Analysis and Synthesis Toolbox

getiv, sortiv, tackon

Return, sort, or append the independent variable values of a VARYING matrix

Syntax

[indv,err] = getiv(mat) 
getiv(mat) 
[out,err] = sortiv(mat,sortflg,nored,epp) 
out = tackon(mat1,mat2)

Description
getiv returns the independent variable values of the VARYING matrix mat. If the input matrix mat is a VARYING matrix, the independent variable is returned as a column vector, indv, and the output err is set to 0. If mat is not a VARYING matrix, then indv is set to empty, and err is set to 1.

sortiv will reorder the independent variable and associated VARYING matrix to be monotonically increasing or decreasing. The optional sortflg is set to 0 (default) for monotonically increasing sorting or nonzero for monotonically decreasing sorting. sortiv can be used in conjunction with tackon to mesh together two different VARYING matrices. The optional third input argument, nored, is set to 0 (default) which does not reduce the number of independent variables even if there are repeated ones. Setting nored to a nonzero value causes repeated independent variables to be collapsed down if their corresponding matrices are the same. If they are not, an error message is displayed and only the first independent variable and corresponding matrix is kept. The output argument err, which is nominally 0, is set to 1 if an error message is displayed. The optional fourth input argument, epp, is a vector used for checking closeness of two variables. If two independent variables are within epp(1), and the norm of the difference between the two matrices at these points is within epp(2), sortiv collapses these two independent variable values down to one. If the two independent variables are within epp(1), and the norm condition is not satisfied, an error message is displayed and out is set to the null matrix. When nored is nonzero, the default value for epp is [1e - 9;1e - 9].

tackon strings together two VARYING matrices placing mat1 on top of mat2. mat1 and mat2 must have the same row and column dimensions.

Examples
The frequency response VARYING matrix from the frsp example is a two-input/two-output matrix containing 30 points. These independent variables vary from 0.1 rad/sec to 100 rad/sec.

minfo(sysg)
varying: 30 pts2 rows2 cols
seeiv(sysg)

1.000e-01    1.269e-01    1.610e-01    2.043e-01    2.593e-01
3.290e-01    4.175e-01    5.298e-01    6.723e-01    8.532e-01
1.083e+00    1.374e+00    1.743e+00    2.212e+00    2.807e+00
3.562e+00    4.520e+00    5.736e+00    7.279e+00    9.237e+00
1.172e+01    1.487e+01    1.887e+01    2.395e+01    3.039e+01
3.857e+01    4.894e+01    6.210e+01    7.880e+01    1.000e+02

Typing getiv without any arguments outputs a brief description of its calling sequence. All µ-Tools commands have this feature. The xtract command selects the independent variables between 1 and 5 rad/sec and the getiv command returns these independent variables from sysg and stores them in indv.

getiv
usage: [indv,err] = getiv(mat)
[indv] = getiv(xtract(sysg,l,5));
indv'
ans =
1.0826    1.3738    1.7433    2.2122    2.8072
3.5622    4.5204

The sortiv command (with an optional second argument) resorts the independent variable of the frequency response of sys in decreasing order.

syslg = sortiv (xtract ( sysg ,1 , 5 ) , 1 ) ;
seeiv(syslg)

4.520e+00   3.562e+00   2.807e+00   2.212e+00   1.743e+00
1.374e+00   1.083e+00

Algorithm
getiv and sortiv manipulate VARYING matrices.

See Also
indvcmp, sort, xtract, xtracti

genmu h2norm, hinfnorm