       Re: Why IntervalBisection can't operate on InterpolatingFunction

• To: mathgroup at smc.vnet.net
• Subject: [mg53766] Re: Why IntervalBisection can't operate on InterpolatingFunction
• From: "Astanoff" <astanoff at yahoo.fr>
• Date: Thu, 27 Jan 2005 05:40:58 -0500 (EST)
• References: <ct4gg2\$aqi\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```An example of what I would do if I were you :

In:=
sol=NDSolve[y''[x] == -y[x] && y == 0 && y' == 1.,y[x],{x,0,30}]

Out=
{{y[x] -> InterpolatingFunction[{{0.,30.}},<>][x]}}

In:=
t=Table[FindRoot[(y[x]/.sol[]) == 0,{x,u}],{u,0,30,0.1}];

In:=
Union[t,SameTest -> (Abs[(x/.#2)-(x/.#1)] < 10^-5&)]

Out=
{{x -> -0.007339502277553871}, {x -> -3.623051082982261*^-21},
{x -> 3.1415927483622084}, {x -> 6.283185408412805},
{x -> 9.4247780931598}, {x -> 12.566370764359306},
{x -> 15.707963453833294}, {x -> 18.849556119270865},
{x -> 21.991148799043714}, {x -> 25.132741498078957},
{x -> 28.274334175842473}, {x -> 31.43186632880639},
{x -> 33.01000282339253}}

v.a.

```

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