VB sqrt problem

**Unipop** · 10-02-2016, 07:53 AM

Hello!
Have a assignment for high school in Excel Visual basics.
So I wrote function func = sqrt(x + 3) and when i type in cell that x = (-4) or less it shows #VALUE! and no matter what I write in arguments it never changes.
I even wrote in arguments that :
If x < (-3) Or x = (-3) Then
func = "error"
But it does not work for me.
I am new to Visual basics.
I guess it is somehow connected to #NUM! error or do I need more arguments, even though I can't really solve it.
Please help!

**cytop** · 10-02-2016, 08:10 AM

assignment for high school

Did you miss the class on Square Roots?

THe square root of a negative number is an imaginary number, not a real number, so Excel cannot calculate it.

You should read this

**Unipop** · 10-02-2016, 08:21 AM

Yea, I know that and that is not the problem, the problem is that I have to prevent it and when someone wants to do that, I have to give back aswer with
String = "error".
But instead I get #VALUE! error.

**cytop** · 10-02-2016, 08:27 AM

I have to prevent it ...

Helps if you actually mention that in the first place. Excel has some Functions to handle errors.

You can also use the IF() Function to test the input value and return a message if invalid or the actual result if valid.

**MrShorty** · 10-02-2016, 10:25 AM

It is difficult to understand your question without seeing the code that you have.

If it will help, in this tutorial http://www.excelforum.com/tips-and-t...uild-udfs.html :

 function quadratic(a as double, b as double, c as double)
stop
disc=b^2-4*a*c
if disc<0 or a=0 then
quadratic="error"
exit function
end if
quadratic=disc
end function

This is one of the intermediate stages and shows how I might handle the "error" when the discriminant for the quadratic equation is negative (seems like a very similar problem to what you describe here).