black — Black's diagram (Nichols chart)
black( sl,[fmin,fmax] [,step] [,comments] ) black( sl,frq [,comments] ) black(frq,db,phi [,comments]) black(frq,repf [,comments])
list ( linear system
real scalars (frequency bounds)
row vector or matrix (frequencies)
row vectors or matrices (modulus, phase)
row vectors or matrices (complex frequency response)
Black's diagram (Nichols'chart) for a linear system
sl can be a continuous-time or
discrete-time SIMO system (see
syslin). In case of
multi-output the outputs are plotted with different symbols.
The frequencies are given by the bounds
fmax (in Hz) or by a row-vector
(or a matrix for multi-output)
step is the ( logarithmic ) discretization step.
calfrq for the choice of default value).
comments is a vector of character strings
db,phi are the matrices of modulus (in Db) and
phases (in degrees). (One row for each response).
repf matrix of complex numbers. One row for each
To plot the grid of iso-gain and iso-phase of
y/(1+y) use chart().
Default values for
sl is continuous-time or
0.5/sl.dt (nyquist frequency)
sl is discrete-time.
s=poly(0,'s') h=syslin('c',(s^2+2*0.9*10*s+100)/(s^2+2*0.3*10.1*s+102.01)) clf();black(h,0.01,100); chart(list(1,0)); h1=h*syslin('c',(s^2+2*0.1*15.1*s+228.01)/(s^2+2*0.9*15*s+225)) clf() black([h1;h],0.01,100,['h1';'h']) chart(list(1,0));