NB. J Phrases Section 10E. Approximation

d0=: ^.@]  ^@(] +/ .* %.) 1:,.[ NB. Exponential fit of x and y
d1=: ] (] +/ .* %.) 1: ,. [     NB. Linear least squares fit of x and y
d2=: [: ^ 1&,.@[ %.~ ^.@]       NB. a and b such that y is approx. a * b^x</sup>
d3=: 1&,.@[ %.~ ]               NB. a and b such that y is approx. a + b*x
