Re: Plot works in Mathematca 7 but not in Mathematica 8

*To*: mathgroup at smc.vnet.net*Subject*: [mg115866] Re: Plot works in Mathematca 7 but not in Mathematica 8*From*: DrMajorBob <btreat1 at austin.rr.com>*Date*: Sun, 23 Jan 2011 05:36:25 -0500 (EST)

Right you are. It's still a version 8 bug, I think, either way! Bobby On Sat, 22 Jan 2011 20:37:16 -0600, 1.156 <rob at piovere.com> wrote: > Bobby, I'm not yet convinced you're right about that. Please consider: > > f := Abs[((kn^2 - (kr + ki I)^2)* > (4 h (Log[4 h/a] - > NIntegrate[(1 - Exp[I (kr + ki I) y Cos[kn y]])/y, {y, 0, > 2}]) + > I/((kr + ki I) + kn) (Exp[I 2 ((kr + ki I) + kn) h] - 1) + > I/((kr + ki I) - kn) (Exp[I 2 ((kr + ki I) - kn) h] - 1) ) - > (kn^2 + (kr + ki I)^2) 2/kn NIntegrate[ > Exp[I (kr + ki I) y] Sin[kn y]/y, {y, 0, 2}])] > h = 1; a = 0.0001; kn = \[Pi]/h; kr = 3.088; > Plot[f, {ki, -0.105, -.085}] > > This has no _?NumericQ in it and works in M8 here. > $Version > "8.0 for Microsoft Windows (32-bit) (November 7, 2010)" > > Rob > > On 11/01/22 19:20 PM, DrMajorBob wrote: >> It's not SetDelayed that fixed the Plot (though it's necessary for other >> reasons)... it's _?NumericQ that does it. >> >> Bobby >> >> On Sat, 22 Jan 2011 16:32:50 -0600, 1.156 <rob at piovere.com> wrote: >> >>> Sir, the plot looks right. It appears that the scheme of using set >>> delayed for the plotted function allows it to work on M8. Why, I have >>> no idea. Thank you for your help. >>> Regards, Rob >>> >>> On 11/01/22 15:28 PM, DrMajorBob wrote: >>>> I also got an empty Plot in version 8, but I found two solutions. >>>> >>>> First, the awkward one: >>>> >>>> h = 1; a = 0.0001; kn = Pi/h; kr = 3.050; >>>> ListPlot[pts = >>>> Table[{ki, >>>> Abs[((kn^2 - (kr + ki I)^2)*(4 h (Log[4 h/a] - >>>> NIntegrate[(1 - Exp[I (kr + ki I) y Cos[kn y]])/y, {y, 0, >>>> 2}]) + >>>> I/((kr + ki I) + kn) (Exp[I 2 ((kr + ki I) + kn) h] - 1) + >>>> I/((kr + ki I) - kn) (Exp[I 2 ((kr + ki I) - kn) h] - >>>> 1)) - (kn^2 + (kr + ki I)^2)* >>>> NIntegrate[ >>>> Exp[I (kr + ki I) y] Sin[kn y]/y, {y, 0, >>>> 2}])]}, {ki, -0.23, -.10, .001}], Joined -> True] >>>> >>>> Is that what the plot should look like? >>>> >>>> If it is, you get a good approximation to the function with >>>> >>>> f = Interpolation@pts; >>>> Plot[f@ki, {ki, -.23, -.1}] >>>> >>>> Finally, the simple solution: >>>> >>>> h = 1; a = 0.0001 // Rationalize; kn = Pi/h; kr = 3.050 // >>>> Rationalize; >>>> g[ki_?NumericQ] := >>>> Abs[((kn^2 - (kr + ki I)^2)*(4 h (Log[4 h/a] - >>>> NIntegrate[(1 - Exp[I (kr + ki I) y Cos[kn y]])/y, {y, 0, >>>> 2}]) + I/((kr + ki I) + kn) (Exp[ >>>> I 2 ((kr + ki I) + kn) h] - 1) + >>>> I/((kr + ki I) - kn) (Exp[I 2 ((kr + ki I) - kn) h] - >>>> 1)) - (kn^2 + (kr + ki I)^2)* >>>> NIntegrate[Exp[I (kr + ki I) y] Sin[kn y]/y, {y, 0, 2}])] >>>> Plot[g@ki, {ki, -0.23, -.10}] >>>> >>>> Bobby >>>> >>>> On Sat, 22 Jan 2011 02:24:31 -0600, 1.156 <rob at piovere.com> wrote: >>>> >>>>> I've found very little to complain about using Mathematica 8 but I >>>>> just ran into a >>>>> Plot which only displays the two plot axes, no graph. Fortunately I >>>>> still have Mathematica 7 installed and found that Mathematica 7 Plots >>>>> this same code nicely. >>>>> Can anyone give me clues on what may make this work correctly in >>>>> Mathematica 8? >>>>> Code below, thanks. >>>>> >>>>> *************** >>>>> h = 1; a = 0.0001; kn = Pi/h; kr = 3.050; >>>>> Plot[Abs[((kn^2 - (kr + ki I)^2)* >>>>> (4 h (Log[4 h/a] - >>>>> NIntegrate[(1 - Exp[I (kr + ki I) y Cos[kn y]])/y, {y, 0, 2}]) + >>>>> I/((kr + ki I) + kn) (Exp[I 2 ((kr + ki I) + kn) h] - 1) + >>>>> I/((kr + ki I) - kn) (Exp[I 2 ((kr + ki I) - kn) h] - 1) ) - >>>>> (kn^2 + (kr + ki I)^2)* >>>>> NIntegrate[ >>>>> Exp[I (kr + ki I) y] Sin[kn y]/y, {y, 0, 2}])], {ki, -0.23, -.10}] >>>> >>>> >>> >> >> > -- DrMajorBob at yahoo.com