14.1.4                    Limitations

Displaying the results of postprocessings requires data transfer between GPU's and CPU's accessible memory. Operation is rather slow. It is negligible through single usage but clearly noticeable in dynamic drawing during simulation mode.

Computations of volume envelope for total Poynting Vector and energy in dens regions are performed on CPU. This requires data transfers every FDTD iteration therefore whole operation is noticeably slow.

Older Nvidia cards from GeForce family (without driver support for CUDA 7.0 or higher) are susceptible to display driver replacement by Windows Remote Desktop (RD). In this case QW-Simulator GPU will not run using RD. The user may resort to other remote desktop software like VNC (Virtual Network Connection) to alleviate this limitation. Some newer cards might require driver update to make RD available.

QW-Simulator GPU and QW-Simulator MultiGPU does not handle Floating Point Overflow. A field value may exceed the maximum value allowed by the single precision floating point format. In such a case the fields value displayed in the 2D/3D Fields Distribution window are null. Note that an error message is not displayed. The simulation continues while it is a user's responsibility to estimate, if an error has occurred. Please use a regular CPU version (not QW-Simulator GPU or QW-Simulator MultiGPU) to detect such a situation. Its typical outcome is a drastic change of fields to zero or postprocessing results to infinity (“INF”).