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## Main Question or Discussion Point

**Area under Curve REVERSED!!**

ok now I have got a plot b/w x & y, which produced a curve

using trapz function I evaluated the area

now the important thing is that I have to take say 10% of the evaluated area & want to find at which coordinates 10% of the caculated area approaches to; similarly which coordianes correspond to 20% 30% of the original calculated area

**Code is**

x=[0.8 0.7125 0.6375 0.534 .381 0]

x =

0.8000 0.7125 0.6375 0.5340 0.3810 0

>> conversion=x;

>> y=[1/0.4 1/.8 1/1.2 1/2 1/4 0]

y =

2.5000 1.2500 0.8333 0.5000 0.2500 0

>> rate=y;

>> plot(conversion,rate)

>> color=[010];

>> basey = min(0,min(y));

h = fill([x x(end) x(1)], [y basey basey], color);

>> %area under curve shaded

>> area=trapz(conversion,rate)

area =

-0.4162

>> area=trapz(conversion,-rate)

area =

0.4162