说明：  This function generates Walsh Codes. The difference between this function and other functions available to generate walsh code is : 1. you can call this function directly in your script, you will have to pass only the value of a (length of code is 2 ^ a) 2. this function can return you both the walsh matrix and randomly selected row (you may need just one sequence for your script) for usage details refer to file. syntax: var = walshcode(x) x = (0, 1, 2, 3, 4, ....) ==> length of code y = 2 .^ x = (1, 2, 4, 8, 16, ....) by default the var will be a matrix (y x y) for getting any one sequence go to the file and invoke another built in function by removing (refer file)