 <p>My experience with <a href="http://www.ni.com/lwcvi/" rel="nofollow">LabWindows CVI</a> is that its built-in libraries are more geared to instrumentation (GPIB, analog and digital I/O, motion control, and so forth) and data display (GUI widgets like meters, sliders, switches, LEDs, simple graphs), rather than extensive libraries of numeric, statistical, or analytic routines. The development environment that comes with Labwindows CVI is pretty decent -- they have a drag-and-drop GUI building interface that makes it easy to position controls within windows and wire them up to your C code, if that matters to you.</p> <p>But for your analytic needs, you might be better served with a product like <a href="http://www.mathworks.com/products/matlab/index.html" rel="nofollow">Matlab</a> or <a href="http://www.exelisvis.com/idl-home/idlhandyguide.aspx" rel="nofollow">IDL</a>, especially if your work is heavy on the plotting/visualization end of things. </p> <p>If you want to stick with C, the <a href="http://www.gnu.org/software/gsl/" rel="nofollow">GNU Scientific Library</a> has a pretty extensive set of statistical and analytic routines. </p>