hi fellows, i have been reviewing a paper on equation of state where i have to find a relation between pressure and density using the ideal form of

P=@*r, where P=pressure and r=density

now i have got both P and r as a function of parameter t.

r=k(sinh(t)-t)

P=1/3k (sinh(t)-8sinh(0.5t)+3t)

and i have drawn a parametric graph of p=p(r)

it's sort of a straight line as expected and what i need to do now is to find a linear or non linear relationship that best explains the pressure and density relationship. in other words finding that @ in P=@r relationship.

can you plz tell me how can i do it?

from the graph tracing the slop or from the formulas ?

regrads in advance