The Excel Islogical function tests if a supplied value (or expression) evaluates to a logical (ie. evaluates to True or False). If so, the function returns TRUE; Otherwise, it returns FALSE.
The syntax of the function is:
Where the supplied 'value' argument is either a simple value, a value returned from a formula, or a reference to a cell containing a value.
The spreadsheets below show several examples of the Excel Islogical function. The spreadsheet on the left shows the formulas used, and the spreadsheet on the right shows the results:
Formulas:

Results:

Note that the Islogical function in cell A3 would still return TRUE, even if cells B1 and B2 were not equal, as the Islogical function it is simply testing if the expression 'B1=B2' evaluates to a logical value.