mahmood questions

• Checking for variable to be non-empty in bash
• Appending row to dataframe with concat()
• undefined reference to `tan' but math.h has been included
• how to change the color of an arrow
• operator== overloading considering non-static member function
• yet another issue with call by value|reference
• Is it possible to change point size in gnuplot
• creating an array from a command line option (python::optparse)
• printf() in my CUDA kernel doesn't result produce any output
• Changing default python to another version

mahmood answers