In order for a chart to ignore a cell (i.e., not treat it as zero), I enter
the #N/A error (by typing or returning the function =NA()) in the cell. But
this will not work if I want functions such as STDEV(), MAX(), etc., to
ignore the cells; they will return an error if any cell in the argument range
is an error. For functions to ignore a cell, I must enter (or my formula
must return) a null string (="") in the cell.

Is there a way I can I satisfy the requirements of both charts and functions
to ignore a cell (without needing to maintain two separate columns, and with
as least monstrous a formula as possible)? Any insights appreciated.