Julia set的代码总是在CUDA C中生成灰色图像。

I've written the following code for generating a Julia set fractal in CUDA C/C++ with some help from online sources. I've been trying for hours now, but I'm unable to figure out as to why this always generates a grey image rather than the one I get when I run the CPU code. I'm new to CUDA C and parallel programming, and I'm currently referring to I've written the following code for generating