Pseudo-random number generator(PNG) is necessary in the computing works using Monte-Carlo method.The main error lies in the calculation of pseudo-random number to influence the accuracy of the calculation by the Monte-Carlo method.In this paper,a new more sufficient method through which one can hope a better outcome-the STTDMR (symmetry test in two dimension media radiation)is presented.The STTDMR is feasible under several of conditions to test unlimited the PNG.Good generators may be distinguished from bad ones more successfully in further level.The STTDMR is used to test not only properties of pseudo-random numbers but also the correctness of the probability models.In order to give a full view of the STTDMR,the STTDMR is applied to test several PNGs,and finally a PNG-ZH which is better than traditional PNG in many ways is obtained.

A ray split-off and tracing approach is presented to analyze the apparent spectral reflecting performance of a semitransparent fluid layer with undulant surface.For parallel incidence and diffuse incidence of the spectral radiation,the regular ray tracing and the inverse ray tracing are separately employed to realize tracing the ray split-off process.With a clear and simple solving idea, the approach possesses a high calculating rate and small demands for the EMS memory,and is flexible for this kind of problems.The results of the calculating example show the following facts.For diffuse incidence of the spectral radiation,the undulant curve of the surface lowers the reflecting ability of the fluid layer.While for parallel incidence of the spectral radiation,two kinds of different influences on the reflecting ability may be caused by the undulant curve.