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Scilab help >> CACSD (Computer Aided Control Systems Design) > Plot and display > phaseplot


frequency phase plot

Calling Sequence

phaseplot(sl,fmin,fmax [,step] [,comments] )
phaseplot(frq,db,phi [,comments])
phaseplot(frq, repf [,comments])



a single input multiple output (SIMO) linear dynamical system (see syslin).


real scalar: the minimum frequency (in Hz) to be represented.


real scalar: the maximum frequency (in Hz) to be represented.


real scalar: the frequency discretization step (logarithmic scale)). If it is not specified the alorithm uses adaptative frequency steps.


a character string vector: the legend label to be associated with each curve. Optional value is the empty array.


a row vector or an n x m array: The frequency discretization in Hz.


an n x m array: the magnitudes corresponding to frq. This argument is not used, it only appears to make phaseplot have the same calling sequence as gainplot and bode.


an n x m array: the phases in degree corresponding to frq. The phaseplot function plots the curves frq(i,:) versus phi(i,:)


an n x m complex array. The phaseplot function plots the curves frq(i,:) versus phase(repf(i,:))


This function draws the phase of the frequency response of a system. The system can be given under different representations:

  • phaseplot(sl,...) case

    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.

    In this case the frequencies can be given by:

    • the lower and upper bounds in Hz fmin, fmax and an optional frequency step step. The default values for fmin and fmaxare 1.e-3, 1.e3 if sl is continuous-time or 1.e-3, 0.5/sl.dt (nyquist frequency) if sl is discrete-time. If the step argument is omitted the function use an adaptative frequency step (see calfrq).

    • a row vector or a 2D array frq which gives the frequency values in Hz. 2D array can be used for multi-output systems if one wants to have different frequency discretization for each input/output couple.

  • phaseplot(frq,...) case

    This case allows to draw frequency phase plots for previously computed frequency responses. The frequency response can be given either by it's complex representation repf or by it's magnitude phase representation db, phi.

    frq and repf must be row vectors or n x m arrays (each row represent an input/output couple).

The datatips tool may be used to display data along the phase curves.


                   ["$\frac{s^2+18 s+100}{s^2+6.06 s+102.1}$";
                    "$\frac{s^2+3.02 s+228.01}{s^2+27 s+225}$"])

See Also

  • bode — Bode plot
  • gainplot — magnitude plot
  • repfreq — frequency response
  • calfrq — frequency response discretization
  • datatips — Tool for placing and editing tips along the plotted curves.


5.4.0 Function phaseplot introduced.
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Last updated:
Tue Apr 02 17:36:21 CEST 2013