gnuplot script used to generate the above plot:

set yrange [-2.5:2.5]  

set xrange [-4.7124:4.7124]

unset border              

set arrow from -5,0 to 5.5,0  

set arrow from 0,-2.7 to 0,2.8    

set key at -5,2.2

set grid

set size square

plot sin(x) w p pt 6, cos(x) w p pt 7, tan(x) lw 2, 1/tan(x) lw 2

==============

Note that there are no cosecant, secant, and cotangent functions in gnuplot - but you can create them yourself by writing:

gnuplot> cosec (x) = 1 / sin (x)

gnuplot> sec (x) = 1 / cos (x)

gnuplot> cot (x) = 1 / tan (x)

More information about gnuplot avaliable at:

http://faraday.elec.uow.edu.au/subjects/spring/ecte212/gnuplot.pdf