Positivity preserving interpolation using rational bicubic spline

This paper discusses the positivity preserving interpolation for positive surfaces data by extending the c 1 rational cubic spline interpolant of karim and kong to the bivariate cases. the partially blended rational bicubic spline has 12 parameters in the descriptions where 8 of them are free parameters. the sufficient conditions for the positivity are derived on every four boundary curves network on the rectangular patch. numerical comparison with existing schemes also has been done in detail. based on root mean square error (rmse),our partially blended rational bicubic spline is on a par with the established methods. © 2015 samsul ariffin abdul karim et al.