Finding area of a wave

Hi Assume that, an output of a function(in simulink) is random sine-wave. That random sine-wave is originating at 0 (zero). how can i find out area for the wave above and below origin (Zero). Any logic?

   ...             . .             .
  .   .           .   .           .
 .     .         .     .         .
. Area1 .       . Area3 .       .
0________._____._________._____._______
          .Area2.         .   .
           .   .           ...
            ...

Answer 1

[Image Analyst]

I don't have Simulink so I'm not sure, but do you have the signal as an array? If so can't you just do

positiveSum = sum(signal(signal>0));
negativeSum = -sum(signal(signal<0));

If you need the areas in each half-cycle, then you'll have to find the zero crossings first.