initial commit / add all books

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diff --git a/27/CH7/EX7.2.5/Example_7_2_5.sce b/27/CH7/EX7.2.5/Example_7_2_5.sce
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+function xd=linear725(t,x)

+    xd(1)=(x(2));         //x(dot);   x(2) means y.

+    xd(2)=-x(1)-x(2)+x(1)^2+x(2)^2;     //y(dot);   x(1) means x.; 

+  endfunction

+  bound=[-15,-15,15,15];        //Bounds of x-axis and y-axis as [xmin ymin xmax ymax], change them according to your needs.

+  nrect=22;     //increase it to get more number of curves, i.e. more information will be available.

+  set(gca(),"auto_clear","off")        //hold on

+  x=linspace(bound(1),bound(3),nrect);

+  y=linspace(bound(2),bound(4),nrect);

+  x0=[];

+ 

+ for i=1:22

+     x0=[x(i);y(i)];

+     t0=0;

+     t=0:0.01:6000;

+     xout=ode(x0,t0,t,linear725);

+     plot2d(xout(1,:),xout(2,:));

+ end

+ xtitle('Phase Portrait','x-axis ( x )','y-axis ( y )')
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