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∫

π/2

sin x dx = 1

0.5

Figure 8: y = sin x plotted with boundaries π/2 and π for integration shown.

The code for ﬁgure

set terminal fig monochrome size 8 5 metric textspecial
set output "plot/integral.fig"

x1 = -0.1
x2 = 5
y1 = -0.5
y2 = 1.5
# Set range to display:
set xrange [x1:x2]
set yrange [y1:y2]

# Set zero axis. Arrow head and label must be done manually I guess:
set zeroaxis lt 1 lw 2
# Arrows from origin to somewhere, with filled head and 1.5 char length, 20 deg
set arrow to x2,0 head size character 1.5,20 filled
set arrow to 0,y2 head size character 1.5,20 filled
# Labels at arrows head, offset 1 character length:
set label "$y$" at 0,y2 offset character 1
set label "$x$" at x2,0 offset 0, character 1

# Remove border
unset border

# Set tics at axis:
set xtics axis ("$\\frac{\\pi}{2}$" pi/2, "$\\pi$" pi)
set ytics axis 0,0.5,1

unset key

set label "$\\int_{\\pi/2}^{\\pi} \\sin x \\thinspace \\textrm d x = 1$" at 3,0.5 left

# Must for some reason plot the line again when outputing to fig:
plot "data/integral.dat" using 1:2:3 with filledcurves, \
"data/integral.dat" using 1:2 with lines 1