why won't this plot?

for i = 1:length(xaxis); if xaxis(i) >0; plot(xaxis(i),yaxis(i)); end

end;

xaxis and yaxis have numbers. I always get a blank plot space

Answer 1

[Steven Lord]

% Sample data
xaxis = -2*pi:0.1:2*pi;
yaxis = sin(xaxis);

% Determine the points with positive x coordinates and plot them
positiveXAxisMask = xaxis > 0;
plot(xaxis(positiveXAxisMask ), yaxis(positiveXAxisMask ), 'x')

% Let's plot the negative x coordinates as well for illustration
hold on
plot(xaxis(~positiveXAxisMask ), yaxis(~positiveXAxisMask ), 'o')

[Don]

yay! this one worked. I accepted the earlier answers too quickly

Answer 2

[Massimo Zanetti]

Yes, because you are plotting just on point. Better try this:

plot(xaxis,yaxis)

Answer 3

[Gareth Thomas]

You need to add the hold on command. Try this:

for i = 1:length(xaxis); hold on;if xaxis(i) >0; plot(xaxis(i),yaxis(i),'x'); end; end;

Notice the 'x' which helps you see it.

Answer 4

[Gareth Thomas]

for i = 1:length(xaxis); hold on ;if xaxis(i) >0; plot(xaxis(i),yaxis(i),'x'); end; end;