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define generate # Usage: loop N generate; $1=Counter; $2=N; uses \9.
set $1 $1 + 1 # Increment the counter.
set \9 4 * pi * (((2 * \10) - $2) / ($2 - 1))
set x[$1] \9 # Set x[i] equal to 4*pi*(((2*i)-N)/(N-1)).
set \9 abs(\9) # \9 now equals abs(x).
set y[$1] cos(\9) / (1 + \9) # Set y[i] equal to cos(|x|) / (1 + |x|).
end
viewport 0.25 0.85 0.3 0.8 # Set the viewport scale.
expand 1.2 # Set the character size.
font 2 # Set the font type.
set \10 0 # Initialize the counter.
loop 100 generate \10 100 # Fill the x and y arrays.
set \0 4 * pi # Save 4 * pi.
limits -\0 \0 -0.5 1.2 # Set the limits as -4pi, 4pi, -0.5, 1.2.
box bcnst bcnstv # Draw the box.
connect # Draw the curve.
symbol 2 # Select the `+' symbol.
points # Draw the points.
expand 1.5 # Set the character size a bit bigger.
mtext T 1.0 0.5 0.5 y = cos(|x|) / (1 + |x|)
expand 1.2 # Reset the character size.
xlabel (x)
ylabel (y)
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