error message 'The end operator must be used within an array index expression.'

Hi,

When I try to plot

plot(H20Vs{1:end,1},H20Vs{1:end,2})
hold on
plot(M20Vs{1:end,1},M20Vs{1:end,2})
hold on
plot(N20Vlin{1:end,1},N20Vlin{1:end,2})
% hold on
% plot(P20Vs{1:end,1},P20Vs{1:end,2})
legend('a' ,'b', 'c', 'd', 'e', 'f', 'h', 'l', 'm', 'n')

I recieve this error message 'The end operator must be used within an array index expression.'

Does anyone have any idea why this could be happening? I noticed the last two plot functions don't cause this issue, only the first one.

Cheers

Answer 1

[Walter Roberson]

It is likely that the error is in code before what was posted. For example,

a(end)=1

The end operator must be used within an array index expression.

This error occurs because end was used to index an array that does not exist yet.

[Walter Roberson]

plot(H20Vs{1:end,1},H20Vs{1:end,2})

This code is very likely wrong, unless H20Vs is a 1 x N cell array for N >= 2.

If H20Vs is a 2 x something cell array, then H20Vs{1:end,1} would do cell array expansion of H20Vs{1,1}, H20Vs{2,1}, H20Vs{3,1} and so on, inserting all of the values "in place" in the command line, and then would do the same thing for H20Vs{1,2}, H20Vs{2,2}, H20Vs{3,2} and so on. The result would be as-if the call

plot(H20Vs{1,1}, H20Vs{2,1}, H20Vs{1,2}, H20Vs{2,2})

had been made. This would plot H20Vs{1,1} against H20Vs{2,1} and H20Vs{1,2} against H20Vs{2,2}. The code would not plot H20Vs{1,1} against H20Vs{2,1} and then plot H20Vs{2,1} against H20Vs{2,2} and so on.

[Stephen23]

H20Vs might be a table, in which case that syntax does not generate a comma-separated list.

[Walter Roberson]

@Stephen23

Good point about tables.