used memory: c-array vs. NSMutableArray

used memory: c-array vs. NSMutableArray

I need to store up to 1.000.000 double values in different arrays. So far
I'm using an NSMutableArray but it looks like the memory usage is huge.
One idea is to use an c-array in order to avoid the storage of objects in
the NSMutableArray. Is there a way to roughly estimate the memory usage of
an NSMutableArray vs. and c-array? (I could not find any information about
the size of an NSNumber-object vs. an primitive like double or float).
Thanks.