The size of a realvec may be changed dynamically; you may also get the current size.
stretch(); getSize(); // for two-dimensional realvecs getCols(); getRows();
If you do not know how big your realvec should be, use
stretchWrite(...). This function checks to make sure that the
realvec is big enough; if not, it resizes the realvec (by doubling the
size) so that it can store the value. This function is much slower than