How to shader the stability area ?

x0 = -5; x1 = 5; Nx = 301;

 y0 = -5;
 y1 = 5;
 Ny = 301;

 xv = linspace(x0,x1,Nx);
 yv = linspace(y0,y1,Ny);
 [x,y] = meshgrid(xv,yv);

 h = x + i*y;

 g = -(118224803259250638877444968353370600910051934512743.*h.^9 - 237428789745399453892107883780168786708111749629870080.*h.^6 + 8178108279897162920859527218771768255678191550351802368.*h.^3 + 196159429230833773869868419475239575503198607639501078528)./(32*(2846779580313514030178888018748426609395855663955.*h.^9 + 1850166005134036192585345683694925738701755489714176.*h.^6 + 31532715869896263823264459664257271745814644580679680.*h.^3 - 6129982163463555433433388108601236734474956488734408704))

 gmag = abs(g); 
 % Plot contours of gmag
 contour(x,y,gmag,[1 1],'b-')

 axis([x0,x1,y0,y1]);
 axis('square');
 xlabel('Real ')
 ylabel('Imag ')
 grid on

Answer 1

[Star Strider]

What region do you want to plot?

You appear to have specified a transfer function. Plotting it is straightforward:

f = @(h) (25.*h.^8 + 765.*h.^7 + 12423.*h.^6 + 131310.*h.^5 + 962910.*h.^4 + 4944240.*h.^3 + 17191440.*h.^2+36741600.*h + 36741600) ./ (25.*h.^8 -765.*h.^7 + 12423.*h.^6 - 131310*h.^5 + 962910.*h.^4 - 4944240.*h.^3 + 17191440.*h.^2-36741600.*h + 36741600);

hv = linspace(0, 20, 1E+3);

figure
plot(hv, f(hv))
grid

The function quickly approaches zero outside the specified limits I defined for ‘hv’.

[sadeem alqarni]

pleas you can plot same this ?

[Star Strider]

I am guessing that you want to plot the image in your Answer.

Try this:

figure
patch([-100 0 0 -100], [-100 -100 100 100], [0.1 0.1 1.0], 'FaceAlpha',0.5)
xlim([-100  100])

Experiment to get the result you want.

[sadeem alqarni]

How to draw f=25.*h.^8 + 765.*h.^7 + 12423.*h.^6 + 131310.*h.^5 + 962910.*h.^4 + 4944240.*h.^3 + 17191440.*h.^2+36741600.*h + 36741600./ 25.*h.^8 -765.*h.^7 + 12423.*h.^6 - 131310*h.^5 + 962910.*h.^4 - 4944240.*h.^3 + 17191440.*h.^2-36741600.*h + 36741600 The same way you draw a picture

[Star Strider]

Run all the code in my original Answer to find out (repeated here):

f = @(h) (25.*h.^8 + 765.*h.^7 + 12423.*h.^6 + 131310.*h.^5 + 962910.*h.^4 + 4944240.*h.^3 + 17191440.*h.^2+36741600.*h + 36741600) ./ (25.*h.^8 -765.*h.^7 + 12423.*h.^6 - 131310*h.^5 + 962910.*h.^4 - 4944240.*h.^3 + 17191440.*h.^2-36741600.*h + 36741600);

hv = linspace(0, 20, 1E+3);

figure
plot(hv, f(hv))
grid

EDIT — (18 Jul 2018 at 01:04 UTC)

Your edited code is entirely different from your previous code.

I am not certain what you want. Filling in the contours with different colours is straightforward with the contourf function:

contourf(x,y,gmag,[0.001 1],'b-');
colormap([1 0 0; 0 1 0])                            % Colour Values < 1 Red, Values >= 1 Green

Change a colormap row to [1 1 1] to make it white if you only want one area coloured.