Curve on specific X and Y coordinates

i would like to graph a curve that passes through the X, Y coordinates

x = [429.245/3, 303.996/3, 287.771/3, 267.384/3, 252.095/3, 239.755/3, 224.149/3, 201.129/3, 0, -198.87/3, 222.745/3, 237.498/3, 249.837/3, 265.127/3, 285.513/3, 301.739/3, 432.098/3]; 
y = [ 20.61/3,   20.61/3,   20.61/3,   16.436/3,  10.8/3,     6.243/3,   2.488/3,   0,       0,    0,        2.488/3,   6.243/3,  10.8/3,    16.436/3,  20.61/3,   20.61/3,   20.61/3];

Answer 1

[John D'Errico]

x = [429.245/3, 303.996/3, 287.771/3, 267.384/3, 252.095/3,239.755/3,224.149/3,201.129/3,0,-198.87/3, 222.745/3,237.498/3,249.837/3,265.127/3,285.513/3,301.739/3,432.098/3]; 
y = [20.61/3, 20.61/3, 20.61/3, 16.436/3, 10.8/3,6.243/3, 2.488/3,0,0,0,2.488/3,6.243/3,10.8/3,16.436/3,20.61/3,20.61/3,20.61/3];
plot(x,y,'-')

Done. Did you really expect some nice smooth well-behaved curve? I hope not. Is there some information you know about the curve? If there is, then how do you expect a computer to know what you know?

Answer 2

[Walter Roberson]

Difficult to say what you want in a curve when it doubles back on itself.

If this is intended as a hysterisis curve then you should say so instead of just giving it as a list of points.

x = [429.245/3, 303.996/3, 287.771/3, 267.384/3, 252.095/3, 239.755/3, 224.149/3, 201.129/3, 0, -198.87/3, 222.745/3, 237.498/3, 249.837/3, 265.127/3, 285.513/3, 301.739/3, 432.098/3]; 
y = [ 20.61/3,   20.61/3,   20.61/3,   16.436/3,  10.8/3,     6.243/3,   2.488/3,   0,       0,    0,        2.488/3,   6.243/3,  10.8/3,    16.436/3,  20.61/3,   20.61/3,   20.61/3];
[sx, idx] = sort(x);
sy = y(idx);
plot(x, y, '-*k'); ylim([-1 8])

plot(sx, sy, '--+b'); ylim([-1 8])

ix = linspace(sx(1),sx(end));
iy = interp1(sx, sy, ix, 'spline');
plot(sx, sy, '--+b', ix, iy, '-.sg'); ylim([-3 8])