#### 1.4.1 New syntax

This version of gnuplot introduces command iteration and block-structured if/else/while/do constructs. See ‘if‘, ‘while‘, and ‘do‘. Simple iteration is possible inside ‘plot‘ or ‘set‘ commands. See iteration. General iteration spanning multiple commands is possible using a block construct as shown below. For a related new feature, see the ‘summation‘ expression type. Here is an example using several of these new syntax features:

          set multiplot layout 2,2
          fourier(k, x) = sin(3./2*k)/k * 2./3*cos(k*x)
          do for [power = 0:3] {
              TERMS = 10**power
              set title sprintf("%g term Fourier series",TERMS)
              plot 0.5 + sum [k=1:TERMS] fourier(k,x) notitle
          }
          unset multiplot

It is now possible to select a column of data from a data file by matching a label in the first row of the file. See columnhead. For example

          plot for [crop in "Oats Peas Beans"] 'data' using "Year":crop