Real Number function

[TheRealVeon]

I am trying to find a real number function or the equivalent in Excel.

I need to evaluate an arccos, but I can only use the real number answers. Here's the formula I'm working with:

Probability.pdf

And here's the Excel file:

Real Numbers.xls

The inputs for each calculation are in column A and the corresponding formulas are in column C. So far I'm only getting a #VALUE error except for one return.

I've checked several books without success and I've done several searches online, but real number is so vague a phrase, none of the search results have been what I'm looking for (mostly dealing with converting text in "real" (actual, not written out) numbers).

Ideally there would be a basic function for this so I would only have to type REAL(ACOS(X)), but that doesn't seem to be the case (or I just haven't found it).

Thanks for the help.

[shg]

IMREAL returns the real part of a complex number. If that doesn't do what you want, provide some more background.

[Richard Buttrey]

Hi,

The ACOS() function requires the cosine of the number you specify, and the cosine must be between -1 and 1.

The result of your ACOS((A4^2+A5^2-9)/(2*A4*A5)) using your inputs falls outside these limits, hence your error.

What do you mean by a real number function?

Rgds

[TheRealVeon]

What I mean is a function like ABS() or SUM() or AVERAGE() which would only return real numbers. My advanced graphing calculator (TI-92) has such a function and when I enter those formulas which give the #VALUE error, I get the correct answer.

I could just type in the same formula on my calculator and change the variables each time, but that would be about 100+ manual calculations by the time I would be through all the data. Doing it in Excel would be much much easier.

Also, the IMREAL() function doesn't work either. Thanks though.

[shg]

If you're looking to get the real part of the acos, you need to take the imaginary arc cosine, which is a lot more complicated than what you have.

Excel can do it, but if you've invested all the effort you choose to, that's fine.