if you plot the 2 formula that give you this
http://www.knewance.com/comparisons/...-catenary.html
or this
http://www.clausentech.com/lchs/dcla...h_Excel_v2.pdf
but if you put the start of the plotting at the same place you can see the catenary can be push ((( like a flex can be pull
http://media.skyandtelescope.com/doc...MirrorFlex.pdf )))
the catenary probalby can be push also
my test just beging
jack 47'N 71'W