Plotting implicit functions via fimplicit

Hello,

I have the following anonymous function:

L = 5000;
F = 11500;
E = 70000;
cP = @(B,H)[H.*(B.^-1)-6, 6.*F.*L.*((B.*H.^2).^-1)-50,...
            4.*F.*L.^3.*((E.*B.*H.^3).^-1)-12.7];

Now I want to plot each curve in the vector via

interval = [0 500 0 500];
fimplicit(cP,interval);

This does not work. I suppose fimplicit expects only one curve and could not handle the vector containig the curves.

So, how can I access the each curve, i.e H.*(B.^-1)-6=0, which are in the vector and pass it to fimplicit so that fimplicit can handle it?

Thanks in advance,

Michael

Answer 1

[Voss]

Apparently (this behavior appears to be undocumented), you can pass a cell array of function handles to fimplicit, as in:

L = 5000;
F = 11500;
E = 70000;
interval = [0 500 0 500];
% cP = @(B,H)[H.*(B.^-1)-6, 6.*F.*L.*((B.*H.^2).^-1)-50,...
            % 4.*F.*L.^3.*((E.*B.*H.^3).^-1)-12.7];
cP = { ...
    @(B,H)H.*(B.^-1)-6, ...
    @(B,H)6.*F.*L.*((B.*H.^2).^-1)-50, ...
    @(B,H)4.*F.*L.^3.*((E.*B.*H.^3).^-1)-12.7, ...
    }

cP = 1×3 cell array
    {@(B,H)H.*(B.^-1)-6}    {@(B,H)6.*F.*L.*((B.*H.^2).^-1)-50}    {@(B,H)4.*F.*L.^3.*((E.*B.*H.^3).^-1)-12.7}

figure
fimplicit(cP,interval);

Since it is undocumented, I don't which MATLAB versions support this, so you may have to use each one separately:

figure
for ii = 1:numel(cP)
    fimplicit(cP{ii},interval);
    hold on
end

[Michael Haag]

@Voss: Perfect thank you, this helps!

Interesting that fimplicit accepts a cell array of function handles.

[Voss]

You're welcome!

Yeah, I was surprised to discover (accidentally, while writing my answer) that the cell array of function handles works. The documentation lists only a function handle as the supported class for the first input to fimplicit (no mention of cell arrays):

https://www.mathworks.com/help/matlab/ref/fimplicit.html#bvds9d6-1-f