Re: Array formulas, piecewise functions

[Oliver Burnett-Hall <olly burnett-hall co uk>]

Stephen R Laniel wrote:
> 1) I'm familiar with array formulas from Excel, such that
> one can do formulas like
>
> =sum(if(and($G$2:$G$30000>=H2,$G$2:$G$30000<H3),1,0))

[...]

> It shares a lot of similarities, apparently, with Excel's
> array formulas, but it's not working for me. How do I have
> to change the Excel formula to make it work in Gnumeric?

=SUM(($G$2:$G$30000>=H2)*($G$2:$G$30000<H3))

This works in Excel too.

> 2) I have a piecewise function defined as follows:
>
> f(t) = (1/2)t^2         , 0 < t < 1
>      = -(t^2 - 3t + 3/2), 1 < t < 2
>      = (1/2)(3-t)^2     , 2 < t < 3
>      = 0                  elsewhere
>
> In Excel, assuming t was in column A, I'd do something like
> so:
>
> =if(and(0<a1,a1<1),.5*a1^2,if(and(1<a1,a1<2),-(a1^2-3*a1+3/2),...))
>
> It's a mess, but that's what I'd do.
>
> I can't get that to work in Gnumeric; it's returning FALSE
> or TRUE when it should be returning a value.

This looks okay.  If you're getting TRUE or FALSE then I guess you're 
missing some arguments to one of the IF functions - double-check them to 
 make sure all of them have three arguments (test, if-true, if-false).

If you can't see anything wrong, post the complete function here.

HTH,

- olly