Re: Array formulas, piecewise functions

[Luciano Miguel Wolf <luciano wolf indt org br>]

Hi Steve,

I'm using the Gnumeric v1.6 and it return numeric values for me, to the
function (2). I used de following expression:

=if(and(0<A1,A1<1),0.5*A1^2,if(and(1<A1,A1<2),-(A1^2-3*A1+3/2),if(and(2<A1,A1<3),0.5*(3-A1)^2,0)))


Luciano Wolf
INdT


Stephen R Laniel wrote:
> Two questions:
>
> 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))
>
> which in this case produce a count of all those cells
> between g2 and g30000 that lie between the values in h2 and
> h3. If column H contains bins for a histogram, this formula
> will list the frequencies for those bins. (Note that one has
> to press Ctrl+Shift+Enter to make this array formula work.)
>
> Gnumeric's documentation for array formulas is confusing:
> http://www.gnome.org/projects/gnumeric/doc/sect-data-formulas.html
>
> 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?
>
> 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.
>
> Can someone give me pointers on representing piecewise
> functions in Gnumeric?
>
> Thanks much,
> Steve
>
>
>
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