Extract population within a specified area

I am trying to determine the population within a circle of a specified radius. I have downloaded a population shapefile from US Census and want to use it to extract the total population within the specified area (i.e. circle). Does anyone know a way to accomplish this? I believe this is something typically done in ARCGIS, but I would like to incorporate this with the rest of my model in MATLAB. Thank you.

[José-Luis]

If I was you, I'd stick to ArcGIS. Different tools are suited for different tasks.

Baring that, I would write a script (Python? whatever tickles your fancy, but that one is well integrated to ArcGIS) and integrate it with Matlab.

If your really want a headache (in my opinion), then I would make sure I had the mapping toolbox and do it natively.

[Stephanie]

Thank you. I just do not have access to ArcGIS and was hoping matlab would accomplish the same task.

[José-Luis]

There are free GIS tools out there. GRASS, Quantum, etc...