xtract, xtracti (Mu Analysis and Synthesis Toolbox)

Extract a specified portion of a VARYING matrix

Syntax

[matout,err] = xtract(mat,iv_low,iv_high) 
[matout,err] = xtract(mat,ivdes) 
[matout,err] = xtracti(mat,indvindex)

Description

xtract extracts a portion of a VARYING matrix. The independent variable associated with a VARYING matrix monotonically increases (like frequency or time). In the first form, xtract is called with three input arguments: a VARYING matrix, a lower bound iv_low, and an upper bound iv_high. The matrix values associated with any independent variables between iv_low and iv_high are extracted, and returned as a VARYING matrix. In the second form, xtract is called with two arguments. The second argument is a vector of desired independent variable values. For each desired value, the matrix from mat with the closest independent variable value (in absolute value) is extracted.

xtracti extracts the value of the VARYING matrix at the specific indices indvindex of the independent variable. Hence indvindex should be an array of positive integers. The extracted matrix is returned as a VARYING matrix.

Examples

Extract ranges of independent variable from a VARYING matrix.

see(mat)
2 rows2 columns

iv = 0.1
    2.9703e+00 - 2.9703e-0li5.9406e+00 - 5.9406e-0li
    3.9604e+00 - 3.9604e-0li7.9208e+00 - 7.9208e-0li

iv = 0.4
    2.5862e+00 - 1.0345e+00i5.1724e+00 - 2.0690e+00i
    3.4483e+00 - 1.3793e+00i6.8966e+00 - 2.7586e+00i

iv = 0.9
    1.6575e+00 - 1.4917e+00i3.3149e+00 - 2.9834e+00i
    2.2099e+00 - 1.9890e+00i4.4199e+00 - 3.9779e+00i
matl = xtract(mat,.3,.8);
see(matl)
2 rows2 columns

iv = 0.4
    2.5862e+00 - 1.0345e+00i5.1724e+00 - 2.0690e+00i
    3.4483e+00 - 1.3793e+00i6.8966e+00 - 2.7586e+00i

matl = xtracti(mat,2);
see(matl)
2 rows2 columns

iv = 0.4
    2.5862e+00 - 1.0345e+00i5.1724e+00 - 2.0690e+00i
    3.4483e+00 - 1.3793e+00i6.8966e+00 - 2.7586e+00i