A good solution to this is the gamma function. There are, relatively speaking, no such simple solutions for factorials no finite combination of sums, products, powers, exponential functions, or logarithms will suffice to express x! but it is possible to find a general formula for factorials using tools such as integrals and limits from calculus. The simple formula for the factorial, x! = 1 × 2 × ⋯ × x, cannot be used directly for non-integer values of x since it is only valid when x is a natural number (or positive integer). "Find a smooth curve that connects the points ( x, y) given by y = ( x − 1)! at the positive integer values for x."Ī plot of the first few factorials makes clear that such a curve can be drawn, but it would be preferable to have a formula that precisely describes the curve, in which the number of operations does not depend on the size of x. The gamma function can be seen as a solution to the following interpolation problem: Gnuplot stats how to#I can get a variable into sprintf into the title, but I have not figured out syntax to load a "cell" value ("cell" meaning row column intersection) into a variable.Īlternatively, if someone can tell me how to use the sum function to total up 522 120 660 (read from the data file, not as constants!) and store that total in a variable, that would obviate the need to have the grand total in the data file, and that would also make me very happy.The gamma function interpolates the factorial function to non-integer values. I want to display the grand total somewhere on my chart, say as the second line of the title or in a label. Those total numbers are displayed at the top of each histogram bar. Plot for 'mydata.dat' every ::1 using i:xticlabels(1) with histogram \įor the benefit of others trying to label histograms, in my data file, the column after the case label represents the total of the rest of the values on that row. Set terminal pngcairo size 1024,768 enhanced font 'Segoe UI,10' My question is: how can I load the grand total value 1976 (next to the word 'total') from the data file and either (a) store it into a variable or (b) use it directly in the title of the plot? lines using the script below - and that works. My data file has this content # data file for use with gnuplot Using data provided by user424855 print y If you don't know the row number where your data is located, but you know it is in the n-th column of a row where the value of the m-th column is x, you can define a function get_data(m,x,n,filename)=system('awk "\$'.m.'=\"'.x.'\"" '.filename)Īnd then use it, for example, as y = get_data(1,"case2",4,"datafile.txt") With labels offset 0,1 title sprintf('total %d', total) Plot for 'mydata.dat' every ::1 using i:xtic(1) notitle, \ Set terminal pngcairo size 1024,768 enhanced So, your plotting script could look like the following: reset These commands require gnuplot 4.6 to work. Stats 'mydata.dat' every ::1 using (sum column(i)) nooutput the same like the previous command, but without using the saved totals) use: # sum all values from columns 3:7 from all rows To sum up all values in the second column, use: stats 'mydata.dat' every ::1 using 2 nooutputĪnd finally, to sum up all values in columns 3:7 in all rows (i.e. Stats 'mydata.dat' every ::::0 using 2 nooutput In your case, to extract the total value, use: # extract the 'total' cell The row and col are specified with every and using, like in a plot command. If it is a single values, you can use the stats command to extract the values. Lets start with extracting a single cell at (row,col).
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