screens.fields.theta_theta_indices(theta, lower=-0.25, upper=0.75)[source] [edit on github]

Indices to pairs of angles within bounds.

Select pairs theta0, theta1 for which theta1 is constrained to lie around theta0 to within (lower*theta0, upper*theta0).

Here, lower=-1, upper=1 would select all non-duplicate pairs that are not on the diagonals with theta1 = ±theta0 (i.e., like np.triu_indices(theta.size, k=1), but also excluding the cross-diagonal; upper=1+epsilon would be identical). But using all off-diagonal points gives too many poor constraints.

The defaults instead select points nearer the top of the inverted arclets, extending further on the outside than on the inside, since on the inside all arclets crowd together.


Grid of angles.

lower, upperfloat

Range of angles for which indices should be returned.