channelflow.org

**This is an old revision of the document!** ----

====== Math 445 lecture 4: log-linear relations ====== Logarithmic plots are useful when the data you're plotting varies over many orders of magnitude. Logarithmic plots can also highlight certain functional relationships ^ plot command ^ functional relationship ^ | **plot(x,y)** ^ $y = mx + b$ ^ | **semilogy(x,y)** | $y = c \; 10^{mx}$ ^ | **semilogx(x,y)** | $y = m \log x + b$ ^ | **loglog(x,y)** | $y = c x^m$ ^ In lecture I will show (1) why each of these functional relationships appears as a straight line in the corresponding plot command and (2) how to estimate the values of the constants from a graph, in order to estimate $y(x)$ as an explicit function.