2. Styles and the key

Three residuals on one plot must be told apart at a glance — also in grayscale print.

call fig%plot(it, rho, title='continuity', lw=2.0_R8P)
call fig%plot(it, mom, title='momentum', dt=2_I4P)
call fig%plot(it(::8), energy(::8), title='energy', with='linespoints', pt=7_I4P, lc='#e51e10')
call fig%set_key(position='outside right top', box=.true.)

wheel: zoom · drag: pan · right drag: box · a resetopen page ↗

• Each series takes the next color of gnuplot's palette, unless lc sets one (any SVG color: '#e51e10', 'red').
• lw is the line width [px], dt the dash type (1 solid, 2–5 dash patterns).
• with='linespoints' draws the points on the line; with='points' the points only. pt picks the point type, as gnuplot: 1 plus, 2 cross, 4 square, 6 circle, 8 triangle, … the odd ones from 5 filled; ps scales it.
• it(::8) plots every 8th iteration: a sparse series reads better with markers.

The key

set_key takes gnuplot's position words: left, right, center, top, bottom, and outside to move it out of the plot, which shrinks to make room. box=.true. draws a frame. 'below' and 'above' put the entries in a row under or over the plot; set_key(.false.) hides it. An empty title keeps a series out of the key.

What you learned

Colors, widths, dash types and point types; the key inside or outside the plot. Reference: Fortran Library, gnuplot Subset.

Next: 3. Axes.