Thanks Russell, that got me pointed in the right direction!
On May 12, 12:57 pm, "russell" <[email protected]> wrote:
> Solve the differential equation F'(x) = E(x) with F(0)=a and F(200) = b.
> The solution is F(X) = c*E(x) +d.
> Giving two linear equations for c and d.
>
> c = (b-a)/(E(200) - 1)
> d = (a*E(200) - b)/(E(200) - 1)
>
> R
>
>
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf
>
> Of Super Steve
> Sent: Tuesday, 12 May 2009 12:12 PM
> To: NZ PHP Users Group
> Subject: [phpug] Exponential Values
>
> I need a bit of help with working out some maths.
>
> I have a number somewhere between 0 and 200 that I want to map onto a
> range between 500 and 250000.
>
> This I can do with the calculation: mapped = (value * (249500 / 200))
> + 500
>
> But now I want the mapped value to rise exponentially between 500 and
> 250000. I.e. in a curved exponential rise.
>
> I know PHP has the exp() function, could I somehow use this?
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