Radial Shading Specification in Adobe Technical Note 5600

Question

Given s, the value of t can be found, which is then passed to the Function
key. The value(s) returned by Function is/are used to determine the color at
the position (x, y). If both roots of the equation are in the domain [0 1], then
the larger value of s defines the color because it comes after the smaller value
and thus overlays it. For values of s outside the domain [0,1], the Extend
values determine how the shading will be painted. The following rules hold
true for pixel coordinates (x,y) satisfying the above equation.
• If the start (first) Extend value is false, then pixels corresponding to values
of s < 0 are left unpainted or are painted with the Background color, if
one is specified.
• If the end (last) Extend value is false, then pixels corresponding to values
of s > 1 are left unpainted or are painted with the Background color, if
one is specified.
• If the start Extend value is true and r[s] >= 0, then pixels corresponding
to the values of s < 0 are painted with the start color.
• If the end Extend value is true and r[s] >= 0, then pixels corresponding to
values of s > 1 are painted with the end color.
The first part is clear when both the roots are within the domain [0 1] but when one root is within the domain and the the other root is outside the domain is not clear.
I am requesting you people here to clearly explain the possible cases considering the roots (s)?
Thanks & Regards
Raquib

Answer 1

Duplicate. See Background color bug with shfill