#Gnuplot fit code#

# X-Axis: House price (in $1000) - Y-Axis: Square meters (m^2) We are going to work with the following data set, called house_price.dat, which includes the square meters of a house in a certain city and its price in $1000. (from Wikipedia, Linear interpolation) Example with a first grade polynomial linear polynomials to construct new data points within the range of a discrete set of known data points. Assume you have a data file where the growth of your y-quantity is linear, you can use Linear interpolation (fitting with a line) is the simplest way to fit a data set. Kelley - gnuplot 5.0, An Interactive Plotting Program) Ranges may be specified to filter the data used in fitting. 1.The basic use of fit is best explained by a simple example: f(x) = a + b*x + c*x**2įit f(x) ’measured.dat’ using 1:2 skip 4 via a,b,c These margins are then added in the same way to the multiplot command as the label settings and we get: # - GRAPH a - GRAPH b - GRAPH c - GRAPH d done all this we will finally get our desired figure which is shown in Fig. As you can see the bottom margin of the two figures in the top is placed at 0.55, the same value the top margin of the two lower graphs start.

The trick is that we use the at screen command to arrange the margins absolutely in the figure. column TMARGIN = 'set tmargin at screen 0.90 set bmargin at screen 0.55' BMARGIN = 'set tmargin at screen 0.55 set bmargin at screen 0.20' LMARGIN = 'set lmargin at screen 0.15 set rmargin at screen 0.55' RMARGIN = 'set lmargin at screen 0.55 set rmargin at screen 0.95' In order to have graphs with the same size and align them without spaces between them we have to set the margins of the individual graphs manually. This comes from the fact that Gnuplot calculates the size of a graph depending on the presence of tics and labels. on the axes are done in a nice way, but the sizes and the spaces between the individual graphs are very bad.

#Gnuplot fit code#

3 A multiplot with reduced axes labeling ( code to produce this figure) These will then be used in the plotting section: # - GRAPH a - GRAPH b - GRAPH c - GRAPH d the axes settings will result in Fig. Set xlabel 'x'' NOYTICS = 'set format y '' unset ylabel' YTICS = 'set format y '%.0f' set ylabel 'y'' nolabel+notics: # x- and ytics for each row resp. Therefore we define macros for the two cases label+tics vs. In order to remove the xtics at a given graph we have to tell this explicitly. Every graph uses the settings from the graph before, if we didn’t change these settings. Here it is the same as with the label settings. Set label 1 'a' plot f( x) with lines ls 1īut the macros are not only useful for the different labels, but also for the other settings of the multiplot.įirst we want to remove the x/y-tics and labels, where they are not necessary. # Placement of the a,b,c,d labels in the graphs POS = 'at graph 0.92,0.9 font ',8'' As you can see in the code block above, the set label command contains the same position for every graph. 2 A straightforward use of the multiplot command to plot four different functions ( code to produce this figure)īut before we fix this we will introduce the use of macros in order to shorten the code a lot. The xtics and the ytics are just the same in every graph and are not needed to be displayed on every graph.įig. As you can see this is not an ideal case to use the space in the figure.

Using this simple approach we will get Fig. If we don’t do that, then on the last graph all four labels will be present. Note that we overwrite the label 1 for every graph. We also added a label to every graph in order to identify them easily in the figure. # - GRAPH a set label 1 'a' at graph 0.92, 0.9 font ',8' plot f( x) with lines ls 1 # - GRAPH b set label 1 'b' at graph 0.92, 0.9 font ',8' plot g( x) with lines ls 1 # - GRAPH c set label 1 'c' at graph 0.92, 0.9 font ',8' plot h( x) with lines ls 1 # - GRAPH d set label 1 'd' at graph 0.92, 0.9 font ',8' plot k( x) with lines ls 1 unset multiplot In a first attempt we just use the multiplot command: # Start multiplot (2x2 layout) set multiplot layout 2, 2 rowsfirst The functions are given by: # Functions (1/0 means not defined) a = 0.9 f( x) = abs( x) < 2 * pi ? a * sin( x) : 1 / 0 g( x) = abs( x) < 2 * pi ? a * sin( x + pi / 2) : 1 / 0 h( x) = abs( x) < 2 * pi ? a * sin( x + pi) : 1 / 0 k( x) = abs( x) < 2 * pi ? a * sin( x + 3.0 / 2 * pi) : 1 / 0įor an explanation of the used syntax to declare the functions have a look at the Defining piecewise functions article. 1 A multiplot with reduced axes labeling and nicely arranged graphs ( code to produce this figure)