gibson:teaching:fall-2014:math445:lecture6-diary
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gibson:teaching:fall-2014:math445:lecture6-diary [2014/09/18 12:16] gibson [Graphical data analysis of log-linear relations] |
gibson:teaching:fall-2014:math445:lecture6-diary [2014/09/18 12:21] (current) gibson [Graphical data analysis of log-linear relations] |
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| ===== Graphical data analysis of log-linear relations ===== | ===== Graphical data analysis of log-linear relations ===== | ||
| - | <code matlab> | + | ==== example 1: a linear relationship ==== |
| - | % ======================================================================= | + | |
| - | % Ok. Let's move on the graphical data analysis | + | |
| + | <code matlab> | ||
| % Load datafile 'data1.asc' into matlab with 'load' command | % Load datafile 'data1.asc' into matlab with 'load' command | ||
| >> D = load('data1.asc'); | >> D = load('data1.asc'); | ||
| Line 271: | Line 270: | ||
| <code matlab> | <code matlab> | ||
| - | % Perfect! The functional relation between y and x is y = -0.49 x + 19 | + | % Perfect! So the functional relation between y and x is y = -0.49 x + 19 |
| + | </code> | ||
| + | ==== example 2: a log-linear relationship ==== | ||
| - | % Ok, let's move on the the next data file and try to figure out its y = f(x) relation. | + | <code matlab> |
| + | % Load the next data file and try to figure out its y = f(x) relation. | ||
| >> D = load('data3.asc'); | >> D = load('data3.asc'); | ||
| >> xdata = D(:,1); | >> xdata = D(:,1); | ||
| >> ydata = D(:,2); | >> ydata = D(:,2); | ||
| - | >> plot(xdata, ydata,'mo-'); grid on | + | >> plot(xdata, ydata,'mo-'); xlabel('x'); ylabel('y'); grid on |
| </code> | </code> | ||
| + | |||
| + | {{ :gibson:teaching:fall-2014:math445:logplot0.png?nolink&400 |}} | ||
| <code matlab> | <code matlab> | ||
| Line 285: | Line 289: | ||
| >> semilogy(xdata, ydata, 'mo-'); xlabel('x'); ylabel('y'); grid on | >> semilogy(xdata, ydata, 'mo-'); xlabel('x'); ylabel('y'); grid on | ||
| </code> | </code> | ||
| + | |||
| + | {{ :gibson:teaching:fall-2014:math445:logplot1.png?nolink&400 |}} | ||
| <code matlab> | <code matlab> | ||
| Line 302: | Line 308: | ||
| >> semilogy(xdata, ydata,'mo-', x, 400*10.^(-0.1*x)); xlabel('x'); ylabel('y'); grid on | >> semilogy(xdata, ydata,'mo-', x, 400*10.^(-0.1*x)); xlabel('x'); ylabel('y'); grid on | ||
| </code> | </code> | ||
| + | |||
| + | {{ :gibson:teaching:fall-2014:math445:logplot2.png?nolink&400 |}} | ||
| <code matlab> | <code matlab> | ||
| Line 310: | Line 318: | ||
| </code> | </code> | ||
| + | {{ :gibson:teaching:fall-2014:math445:logplot3.png?nolink&400 |}} | ||
| <code matlab> | <code matlab> | ||
| % so the functional form is y = 700 * 10^(-0.085 x). | % so the functional form is y = 700 * 10^(-0.085 x). | ||
| + | |||
| + | % Don't ask me why Matlab keeps changing the grid lines on the logarithmic plots... | ||
| </code> | </code> | ||
gibson/teaching/fall-2014/math445/lecture6-diary.1411067770.txt.gz · Last modified: 2014/09/18 12:16 by gibson
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