       Re: hi, how can i accomplish this densityplot?

• To: mathgroup at smc.vnet.net
• Subject: [mg107437] Re: hi, how can i accomplish this densityplot?
• From: çåå <hiphopphysics at yahoo.com.tw>
• Date: Fri, 12 Feb 2010 04:44:53 -0500 (EST)
• References: <hl10vh\$4fn\$1@smc.vnet.net>

```On 2=E6=9C=8811=E6=97=A5, =E4=B8=8B=E5=8D=889=E6=99=8233=E5=88=86, Bob Hanlon <hanl... at cox.net> wrote:
> The problem is that you used patterns (e.g., x_) in the function in the DensityPlot.  You should also restrict the definition of f to numeric arguments since the RHS cannot evaluate without numeric input.
>
> f[x_?NumericQ, y_?NumericQ] :=
>  NIntegrate[r0*Exp[-(r0 + 2*
>         (x^2 + y^2 + r0^2 + 2*r0*
>             ((x^2 + y^2)^0.5)*
>             (Cos[theta0]*(y/(x^2 + y^2)^0.5) -
>               Sin[theta0]*(x/(x^2 + y^2)^0.5))
>           )^0.5)],
>   {r0, 0, Infinity}, {theta0, 0, Pi}]
>
> DensityPlot[f[x, y], {x, -2, 2}, {y, -2, 2}]
>
> Bob Hanlon
>
> ---- "=E7=9C=9F=E5=A5=BD=E5=91=BD" <hiphopphys... at yahoo.com.tw> wrote:
>
> =============
> f[x_, y_] :=
>  NIntegrate[
>   r0*Exp[-(r0 +
>        2*(x^2 + y^2 + r0^2 +
>            2*r0*((x^2 + y^2)^0.5)*(Cos[theta0]*(y/(x^2 + y^2)^0.5) -
>               Sin[theta0]*(x/(x^2 + y^2)^0.5)))^0.5)], {r0, 0,
> Infinity}, {theta0, 0, Pi}]
>
> DensityPlot[f[x_, y_], {x, -2, 2}, {y, -2, 2}]
>
> i entered the code above but mathematica return the error message:
>
> NIntegrate::inumr: The integrand E^(-r0-2 (r0^2+<<1>>+<<1>>+2 r0
> Power[<<2>>] Plus[<<2>>])^0.5) r0 has evaluated to non-numerical
> values for all sampling points in the region with boundaries {{\
> [Infinity],0.},{0,3.14159}}. >>
>
> General::stop: Further output of NIntegrate::inumr will be suppressed
> during this calculation.
>