how can i plot a function with tow variable(x,y) in 2D ?

Answer 1

[Walter Roberson]

You have two input dimensions (x and y) and one output dimension (TR), for a total of 3 dimensions. You need a 3 dimensional plot to represent that.

If for some reason your plot is restricted to two output spatial dimensions, then you will need to encode one of the three dimensions somehow, such as by color or transparency or marker size.

[shawqi saleh]

[Walter Roberson]

Using 0:0.1:100 is not valid for fplot. You need to pass in [0 100] instead.

Note that you are calling fplot with a function of only one variable, which is a different situation than a function of two variables.

You can call

fsurf(@(x,y) sqrt((1+(2*0.1*x).^2)./((1-y.^2).^2+(2*0.1*x).^2)),[0 100 0 100])

but that does not produce a 2D plot.