! Document name: round_grid

!round_grid  08.07.1989.
!internal macro: -

pars dx,dy

addy b/2

let i=a/2
let j=b/2
let k=1"
let l=0.5*i-k
let m=(j/i)*sqr(i*i-l*l)
let n=0.5*j+k
let o=(i/j)*sqr(j*j-n*n)

if (i*i-l*l)<0 then 20

poly_ 4,
0.5*i,0.866*j,0,
l,m,1,
l,-m,0,
0.5*i,-0.866*j,1

poly_ 4,
0.866*i,0.5*j,0,
o,n,1,
-o,n,0,
-0.866*i,0.5*j,1

mulx -1

poly_ 4,
0.5*i,0.866*j,0,
l,m,1,
l,-m,0,
0.5*i,-0.866*j,1

muly -1
poly_ 4,
0.866*i,0.5*j,0,
o,n,1,
-o,n,0,
-0.866*i,0.5*j,1

20:del top
end