MATLAB's $\tt filter()$ function for complex valued data I want to use the filter() function to implement an FIR filter having complex data values as the input to it. For real, I used this function as filter(A,1,B). 

Question : 

Would there be a difference for the corresponding implementation when A and B are in complex domain?
As @msm said, there's no difference. You can refer to Matlab's documentation here: https://www.mathworks.com/help/matlab/ref/filter.html#inputarg_x which says "Complex Number Support: Yes".