hi..Im new in matlab programming. Can someone help me plot 3D graph of y=x-x^2, where z is form negative infinity to infinity.

x=linspace(-0.5,0.5);
y=linspace(-0.5,0.5);
y=x-x.^2;
plot(x,y)

i have done this,but how to plot it into 3D where it will be plane?

[AHMAD AKMAL]

z is from negative infinity to infinity

[Ameer Hamza]

What is z in your equation? What is your idea of plotting to infinity on a finite plane?

[AHMAD AKMAL]

z is undetermine, i just want to fine a plane of function y=x-x^2 in 3D, let take z is from -10 to 10.

Answer 1

[Ameer Hamza]

If you want to plot something the 3d surface plot of this equation

z = y - x + x^2

then try

x = linspace(-0.5, 0.5);
y = linspace(-0.5, 0.5);

[X, Y] = meshgrid(x, y);
Z = Y - X + X.^2;

mesh(X,Y,Z)

[AHMAD AKMAL]

this is not what i mean, to understand my question further, for example, function x^2+y^2 is circle in 2D but in 3D it will be cylinder if the funtion of z=x^2+y^2 and the value of z is fixed , but if we take z=x^2+y^2 where z=0,1,2,3,..., it will be bowl shape in 3D. i want to highlight the cylinder shape. i want to get a plane as in this example of cyclinder that i stated above. pls help me

[Ameer Hamza]

If you just want to extend the 2D shape in third dimension then use

x = linspace(-0.5, 0.5);
z = -10:10;
[X, Z] = meshgrid(x, z);

Y = X - X.^2;
surf(X, Y, Z)