Re: cannot work a "conditional If"
- To: mathgroup at smc.vnet.net
- Subject: [mg130572] Re: cannot work a "conditional If"
- From: Peter Pein <petsie at dordos.net>
- Date: Tue, 23 Apr 2013 00:02:24 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- Delivered-to: l-mathgroup@wolfram.com
- Delivered-to: mathgroup-newout@smc.vnet.net
- Delivered-to: mathgroup-newsend@smc.vnet.net
- References: <kl2nvh$2dg$1@smc.vnet.net>
Am 22.04.2013 09:13, schrieb patrice.haldemann at gmail.com:
> Hi everybody
>
> I am a newcomer in the mathematica world and I have been facing an issue for some days.
>
> I have used mathematica to solve an NDSolve and it has worked well
>
> I have tested expressions with the solution of NDSolve and its has worked well.
>
> Now if I use an expression in an "Conditional If", it does not work.
>
> Thank you for your help
>
>
> See below
>
> signy[t_] := y[t] /. orbit where y[t] is the solution of the NDSolve
>
> signy[1]
>
> {-1.96861}
>
> ang12[t_] := If[signy[t] > 3, 10, 6]
>
> ang12[1]
>
> If[{-1.96861} > 3, 10, 6]
>
>
>
>
Hi Patrice,
You might have noticed the curly braces around the computed value.
Your function signy returns a list with one element, not a value.
signy[t_] := y[t] /. First[orbit]
should work.
Peter