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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) 2010 - INRIA - Serge STEER
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution. The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2.1-en.txt
function nicholschart(modules,args,colors)
[lhs,rhs]=argn(0);
l10=log(10);
ratio=%pi/180;
fig=gcf();
immediate_drawing=fig.immediate_drawing;
fig.immediate_drawing="off";
ax=gca();
old_data_bounds = ax.data_bounds;
nc=size(ax.children,"*")
if nc==0 then
ax.data_bounds=[-360,-40;0,40];
ax.axes_visible="on";
ax.box="on";
ax.tight_limits="on"
ax.title.text=_("Amplitude and phase contours of y/(1+y)")
ax.x_label.text=_("phase(y) (degree)");
ax.y_label.text=_("magnitude(y) (dB)");
else
ax.data_bounds(2,2)=max( ax.data_bounds(2,2),40)
end
ax.clip_state="clipgrf"
phi_min=ax.data_bounds(1,1)
phi_max=ax.data_bounds(2,1)
mod_min=ax.data_bounds(1,2)
mod_max=ax.data_bounds(2,2)
defaultArgs = [1 2 5 10 20 30 50 70 90 120 140 160 180];
defaultModules=[mod_min:20:-35 -30 -25 -20 -15 -12 -9 -6 -3 -2 -1 -0.5 -0.25 -0.1 0 0.1 0.25 0.5 1 2.3 4 6 12];
if exists("modules","local") == 0 | modules == [] then
modules=defaultModules
else
if type(modules)<>1|~isreal(modules) then
error(msprintf("%s: Wrong type for imput argument ""%s"": real floating point array expected\n"),"nicholschart","modules");
end
modules=matrix(modules,1,-1)
end
if exists("args","local")==0 | args == [] then
args=defaultArgs
else
if type(args)<>1|~isreal(args) then
error(msprintf("%s: Wrong type for imput argument ""%s"": real floating point array expected\n"),"nicholschart","args");
end
args=matrix(args,1,-1)
end
//
if exists("colors","local")==0 | colors == [] then
colors=[4 12];
else
if type(colors)<>1|~isreal(colors) then
error(msprintf("%s: Wrong type for imput argument ""%s"": real floating point array expected\n"),"hallchart","colors");
end
if size(colors,"*")==1 then
colors=colors*ones(1,2)
end
end
// convert args to radian and insure negative
args = -abs(args) * ratio;
//initialize handles array for chart entities
chart_handles=[]
// Replication bounds
k1=floor(phi_min/180)
k2=ceil(phi_max/180)
//isogain curves: y as fixed gain and varying phase
//-------------------------------------------------
if modules<>[] then
w=[linspace(-%pi,-0.1,100) linspace(-0.1,0,80) ]
nw=size(w,"*")
for i = 1:prod(size(modules)),
att=modules(i);
y=10^(att/20)*exp(%i*w);
y(y==1)=[];//remove singular point if any
rf=y./(1-y);
[module, phi]=dbphi(rf)
//use symetry and period to extend the curve on [k1*180 k2*180]
p=[];m=[];
S=[];cut=[]
for k=k1:k2-1
if pmodulo(k,2)==0 then
p=[p cut k*180-phi($:-1:1)]
m=[m cut module($:-1:1)]
if att>0 then
str=msprintf("%.2gdB",att)
r=xstringl(0,0,str)
xstring(k*180-phi($)-r(3)/2,module($),str,0,0),
e=gce();
e.font_foreground=colors(1)
S=[e S]
elseif att==0 then
l=find(module>mod_max-r(4),1)
if l<>[] then
xstring(k*180-phi(l-1),module(l-1),"0dB",0,0),
e=gce();
e.font_foreground=colors(1)
S=[e S]
end
end
else
p=[p cut ((k+1)*180)+phi]
m=[m cut module]
if att<0 then
str=msprintf("%.2gdB",att)
r=xstringl(0,0,str)
xstring(p($)-r(3),m($),str,0,0),
e=gce();
e.font_foreground=colors(1)
S=[e S]
end
end
cut=%nan
end
xpoly(p,m)
e=gce();
e.foreground=colors(1),
e.line_style=7;
e.display_function = "formatNicholsGainTip";
e.display_function_data = att;
if size(S,"*")>1 then S=glue(S),end
chart_handles=[glue([S,e]),chart_handles];
end;
end
//isophase curves: y as fixed phase and varying gain
//-------------------------------------------------
if args<>[] then
eps=10*%eps;
for teta=args,
//w = teta produce a 0 gain and consequently a singularity in module
if teta < -%pi/2 then
last=teta-eps,
else
last=teta+eps,
end;
//use logarithmic discretization to have more mesh points near low modules
w=real(logspace(log10(-last),log10(170*ratio),150))
w=-w($:-1:1)
n=prod(size(w));
module=real(20*log((sin(w)*cos(teta)/sin(teta)-cos(w)))/l10)
w=w/ratio
//use symetry and period to extend the curve on [k1*180 k2*180]
p=[];m=[];
for k=k1:k2-1
if pmodulo(k,2)==0 then
p=[p %nan k*180-w($:-1:1)]
m=[m %nan module($:-1:1)]
else
p=[p %nan ((k+1)*180)+w]
m=[m %nan module]
end
end
xpoly(p,m)
e=gce();
e.foreground=colors(2);
e.line_style=7;
e.display_function = "formatNicholsPhaseTip";
e.display_function_data = teta * 180 / %pi;
chart_handles=[e chart_handles]
end;
end
chart_handles=glue(chart_handles)
//reorder axes children to make chart drawn before the black curves if any
for k=1:nc
swap_handles(ax.children(k),ax.children(k+1))
end
fig.immediate_drawing=immediate_drawing;
// reset data_bounds
if rhs == 0 then
ax.data_bounds=[-360,-40;0,40];
else
ax.data_bounds = old_data_bounds;
end
endfunction
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