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.TH nyquist 1 "April 1993" "Scilab Group" "Scilab Function"
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nyquist( sl,[fmin,fmax] [,step] [,comments] )
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nyquist( sl, frq [,comments] )
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nyquist(frq,db,phi [,comments])
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nyquist(frq, repf [,comments])
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: \fVsyslin\fR list (SIMO linear system in continuous or discrete time )
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: real scalars (frequency bounds (in Hz))
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: real (logarithmic discretization step)
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: string vector (captions).
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: vector or matrix of frequencies (in Hz) (one row for
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each output of \fVsl\fR).
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: real matrices of modulus (in Db) and phases (in degree) (one row for each output of \fVsl\fR).
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: matrix of complex numbers. Frequency response (one row
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for aech output of \fVsl\fR)
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Nyquist plot i.e Imaginary part versus Real part of the frequency
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For continous time systems \fVsl(2*%i*%pi*w)\fR is plotted.
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For discrete time system or discretized systems \fVsl(exp(2*%i*%pi*w*fd)\fR
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is used ( \fVfd=1\fR for discrete time systems and \fVfd=sl('dt')\fR for discretized systems )
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\fVsl\fR can be a continuous-time or discrete-time SIMO system (see \fVsyslin\fR).
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In case of multi-output the outputs are plotted with different
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The frequencies are given by the bounds \fVfmin,fmax\fR (in Hz) or by a row-vector
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(or a matrix for multi-output) \fVfrq\fR.
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\fVstep\fR is the ( logarithmic ) discretization step. (see \fVcalfrq\fR for the
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choice of default value).
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\fVcomments\fR is a vector of character strings (captions).
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\fVdb,phi\fR are the matrices of modulus (in Db) and phases (in degrees).
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(One row for each response).
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\fVrepf\fR is a matrix of complex numbers. One row for each response.
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Default values for \fVfmin\fR and \fVfmax\fR are
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\fV1.d-3\fR, \fV1.d+3\fR if \fVsl\fR is continuous-time
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or \fV1.d-3\fR, \fV0.5\fR if \fVsl\fR is discrete-time.
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Automatic discretization of frequencies is made by \fVcalfrq\fR.
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h=syslin('c',(s^2+2*0.9*10*s+100)/(s^2+2*0.3*10.1*s+102.01));
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comm='(s^2+2*0.9*10*s+100)/(s^2+2*0.3*10.1*s+102.01)';
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nyquist(h,0.01,100,comm);
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h1=h*syslin('c',(s^2+2*0.1*15.1*s+228.01)/(s^2+2*0.9*15*s+225))
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nyquist([h1;h],0.01,100,['h1';'h'])
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xbasc();nyquist([h1;h])
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bode, black, calfrq, freq, repfreq, phasemag