Restrict types related to acos/asin.

[samth]

Related to racket/typed-racket#1428.

[bdeket]

Hi,
is this the best way to fix this?
since we are basically doing (acos (cos nr)) we know that if nr is ϵ [Real Flonum] the result of cos is going to (/ should) be in the range [-1 .. 1] and the final result should be one of [Real Flonum] too.
Or am I missing something?

[bdeket]

Managed to find 2 examples that break this:

(let ([A (matrix [[-1.650258747789646e+145 -9.554844718758979e+152]])]
      [B (matrix [[-2.0456892507760957e-130 -1.878691327473384e-122]])])
  (list (matrix-cos-angle A B)
        (matrix-angle A B)))
;; '(1.0000000000000002 0.0+2.1073424255447017e-08i)
(let ([A (matrix [[-1.1137603878341427e-134 1.3937540198551402e-126]])]
      [B (matrix [[1.4964797209265308e+163 -2.0388100696972336e+171]])])
  (list (matrix-cos-angle A B)
        (matrix-angle A B)))
;; '(-1.0000000000000002 3.141592653589793-2.1073424255447017e-08i)

But to me that shows that matrix-cos-angle should be fixed.

[samth]

I don't have any idea if this is the best fix, but I don't think the type of acos or asin can be made more precise.

[samth]

Merged as part of #100