The graph shown is from our fits. If you compare it to the graphs shown in the references, it looks nearly identical which implies that our fits are very good. You want to avoid having water cling to the downstream face of the weir. Water surface downstream of the weir should be at least 0.2 ft. This is an initial check of user input.
Input results in a negative head due to the compiler's machine precision.
American Society for Testing and Materials. International Organization of Standards. U.S. Department of the Interior, Bureau of Reclamation. Water Measurement Manual.