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Implicit function plotting with parameter

Sanjeev Maurya
1#
Sanjeev Maurya Published in 2018-02-14 09:19:06Z

suppose i have a equation like below, i want to plot between x and y with

a=0.000000000142

2*cos(sqrt(3).*y.*a) + 4*cos((sqrt(3).*y.*a)/2).*cos((3.*x.*a)/2) - 1

i want to plot it with respect to 'x' and 'y'. but i did't get anything.

i tried a code as,

syms x y
a = 0.000000000142;
h = @(x,y) 3.*x.*x*a*a + 9.*y.*y*a*a + (9*x.*x.*y.*y*a*a*a*a)./4;
fimplicit(h,[-1 1 -1 1])

another code i tried is as, first i make a function as

function [graphene] = disper(x,y)
graphene = 2*cos(sqrt(3).*y.*a) + 4*cos((sqrt(3).*y.*a)/2).*cos((3.*x.*a)/2)- 1;
a=0.124;
end

and then i call function ezplot as,

ezplot('disper(x,y)', [-10 10 -10 10]);
il_raffa
2#
il_raffa Reply to 2018-02-14 12:09:27Z

Assuming you want to evaluate the function in the (x,y) interval x=(-1,1) and y(-1,1) you can define a grid of X and Y values using the functin meshgrid

Edit

Updated the call to surf (ref. to the comment from Hunter Jiang)

a=0.000000000142
X=[-1:.1:1];
Y=X;
[x,y]=meshgrid(X,Y);
z=2*cos(sqrt(3).*y.*a) + 4*cos((sqrt(3).*y.*a)/2).*cos((3.*x.*a)/2) - 1;
%surf(z)
surf(x,y,z)

Then you can use the function surf to plot the results.

Hope this helps,

Qapla'

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