How to plot parametric curve

I am trying to use matlab code for filters ,how can change the curve from ellipse to an astrioid

[Mathieu NOE]

hello

I don't understand the connection between an elliptical filter and an "astrioid " ??

[alfunsa Prathia]

inplace of ellipse equation i need the equation of astriod x^2/3+y^2/3=a^2/3

[Star Strider]

Please do not name your own function ‘filter’. That ‘overshadows’ a useful MATLAB function and will render the MATLAB function useless.

Answer 1

[Stephan]

https://de.mathworks.com/help/matlab/ref/fplot.html#bu6xntl-12