Contour plot shrinking about its origin

I have a contour plot. I need to shrink it about its origin. I have tried to shrink it as a polygon but it does not work. Could you please help me to overcome the problem? I want shrinking the contour plot about its origin.

I found the code below, but it is for contour plot rotation.

Note: I use matlab ver. 2008.

Any help will be much appreciated.

a = 37;
[x,y] = meshgrid(linspace(-4,4,30));
z = exp(-x.^2/15-y.^2);
contour(x,y,z)
xlim([-5 5])
ylim([-5 5])
axis equal
figure
[C,h] = contour(x,y,z);
rotate(get(h,'children'),[0 0 1],a) 
xlim([-5 5])
ylim([-5 5])
axis equal

Many thanks

Israa

[Ameer Hamza]

Can you explain what do you mean by shrinking the plot?

[israa abdul jabbar]

i want to make 2D transformation(scaling ) for the resulting contour plot. I want to reduce( shrink) the size of final contour plot about its origin .

Answer 1

[KSSV]

You change the x,y limits and use the same z...

a = 37;
[x,y] = meshgrid(linspace(-4,4,30));
z = exp(-x.^2/15-y.^2);
figure(1)
contour(x,y,z)
xlim([-5 5])
ylim([-5 5])
axis equal

[x1,y1] = meshgrid(linspace(-1,1,30));
figure(2)
contour(x1,y1,z)
xlim([-1 1])
ylim([-1 1])
axis equal

[israa abdul jabbar]

Thank you so much, but i want to make 2D transformation(scaling ) for the resulting contour plot. I want to reduce( shrink) the size of final contour plot about its origin .

[KSSV]

Yes this can be done....read about Afine transformations. In there you have a transformation matrix to reduce the scale of your polygons.

[israa abdul jabbar]

i did but it failed because contour polt or contour matrix is not a polygon. Thank you so much

[KSSV]

You have the points in hand...that's enough ..

[israa abdul jabbar]

Below, my code for scaling contour plot, but it failed

center=polygonCentroid(u); % u is my contour plot

scalmatrix=createScaling(center,0.25,0.25); % making scaling matrix

u=transformPoint(u,scalmatrix); % scaling or shrinking process

[c,h] = contour(u,[2 2],'y','linewidth',3);

[Star Strider]

What are these functions:

polygonCentroid
createScaling
transformPoint

and where did you get them?

I can find no references for them either in the MATLAB online documentation or in an Interweb search.

You are doing KSSV a definite disservice by not revealing sources for them or posting the code for them.

[israa abdul jabbar]

iI take these functions from library called "geom2d", i got it from site of mathworks(file exchange). I added that library to my matlab(2008). my code is acceptable and implemented, but the results were wrong.

Note:

geom2d

version 1.25 (427 KB) by David Legland

Geometry library for matlab. Performs geometric computations on points, lines, circles, polygons...

https://github.com/mattools/matGeom

Answer 2

[israa abdul jabbar]

i want to make 2D transformation(scaling ) for the resulting contour plot. I want to reduce( shrink) the size of final contour plot about its origin .