Change arrow direction (placed above different colored bars) according to bars(changing continously).

Hi, Can you please help me with how can i change an arrow direction above bar plot which are 7 different colour bars.The arrow should be directed upward when bars height increasing and downward when bars height decreasing continuously.Thanks!

index = [1 2 3 4 5 6 7];
 axis([0 8 0 0.8])
y=[powlowblue powgreen powyellow poworange powred powpurple powwhite];
for i1=1:numel(y)
text(index(i1),y(i1),num2str(y(i1)),...
'HorizontalAlignment','center',...
'VerticalAlignment','bottom')
text(i1,0.7,'\uparrow');
text(i1,0.6,'\downarrow');
end

how can i get uparrow and downarrow to change according to bars height changing here.

[dpb]

What does "...when bars are increasing and downward when bars are decreasing continuously" mean, precisely?

But, the general answer is use annotation 'arrow' linestyle...see <Annotation>

[Suleman Zafar]

I have (bars) data that is coming continuously from the input (amplifier) and bars height is changing so i have just assigned up and down arrows to all the 7 bars but i do not know how to use them such that arrow direction change with bars height increasing or decreasing.

[dpb]

You mean based on difference of current value vis a vis previous, I gather? If so, you'll have to

1. save the current value
2. compare new value to that previous when it arrives
3. set arrow direction with logic branch (an if...else...end would be likely candidate here), and
4. save the current as the new previous values