Exact split information function for SPC

Split information functions are used in deriving closed-form Extrinsic Information Transfer (EXIT) curves of super-variable nodes (SVNs) in doubly-generalized low-density parity-check (DGLDPC) codes. In this letter, we derive an exact split information function for single-parity-check (SPC) codes. The function is very easy to compute and has been verified against the results obtained using the traversal method.