Warning phase plane plots

I am trying to plot a phase plane. But the code gives me the following warning:

 Warning: Function failed to evaluate on array inputs; vectorizing the function may speed up its evaluation and avoid the need to loop over array elements. 
> In ezplotfeval (line 56)
  In ezplot>ezimplicit (line 257)
  In ezplot (line 153)
  In phaseplane (line 9)

The corresponding line in the code:

f_handle=ezplot(@(x,y)myfunction(x,y,K),[0 K 0 0.025/0.03]);
set(f_handle,'color','k','linestyle','-','linewidth',2);
hold on

Could you please help me to fix it?

Answer 1

[Walter Roberson]

z = b .* x .* (1 - x./(min(K,(P-theta.*y)./q))) - (c.*x) ./ (a+x) .* y;

z = e .* min(1,((P-theta.*y) ./ x) ./ theta) .* (c .* x) ./ (a+x) .* y - d .* y;

[LALE ASIK]

Thank you so much for your help.