Dear all, I'm using the curve() function to plot discharge Q against water depth a. However, I would like to have a graph of water depth a plotted against discharge Q. How can this be done? Minimal working example: S0 = 0.004 n = 0.04 tanalpha = 1.4/1.5 par(mar = c(5,5,1,1)) # b, l, t, r curve((sqrt(S0)/n)*(0.035+(0.7+(x-0.1)/tanalpha)*(x-0.1))*((0.035+(0.7+(x-0.1)/tanalpha)*(x-0.1))/(2*sqrt((0.7/2)^2+0.1^2)+2*sqrt((x-0.1)^2+((x-0.1)/tanalpha)^2)))^(2/3),0.1,1.55, lwd = 3, col = "royalblue4", ann = F, axes = T) title(xlab = parse(text='a~bgroup("[", m, "]")')) title(ylab = parse(text='Q~bgroup("[", m^3/s, "]")')) box() I tried to find the inverse function, but that doesn't seem to exist. Thank you for support, Boudewijn
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