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I begin with a function defined by

c[u_, mH_]

I won't go into details because it comes from countless lines of partial differential equations, boundary conditions and perturbations. But suffice to say it is a rather complex function of two variables.

I have managed to plot the following:

LogLinearPlot[c[u, 135], {u, 100, 10^18}, PlotRange -> All]

That is to say, c(u) at a fixed value of mH.

However, my next step is to plot mH(u) for a fixed c (namely c=0). How do I invert this function in order to achieve this? I've tried

Reduce[c[u, mH] == 0, mH, Reals];

msol = NSolve[coup[u, mH] == 0, mH[u]];

etc... But nothing works. Any ideas? My knowledge of Mathematica is a bit rudimentary.

Ash Arsenault
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    ContourPlot[c[u, mH] == 0, {u, 100, 500}, {mH, 0, 100}] (insert suitable limits). – march Mar 16 '16 at 04:19
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    By the way, is there any way to scale the quantities in your problem so that you don't have to plot all the way out to 10^18? I could see that causing issues. – march Mar 16 '16 at 04:28
  • I used NDSolve here to integrate the derivative of the equation, to construct a numerical approximation to the solution. I've done it several times on this site, as have others, but that's the one that showed up first in a search. – Michael E2 Apr 27 '16 at 15:27

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