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#lang racket/base
(require (for-syntax racket/base) racket/unsafe/ops
"utils.rkt")
(provide (all-defined-out))
;; Returns the interpolated distance of z from za toward zb
;; Examples: if z = za, this returns 0.0
;; if z = zb, this returns 1.0
;; if z = (za + zb) / 2, this returns 0.5
;; Intuitively, regard a use (solve-t z za zb) as "the point between za and zb".
(define-syntax-rule (solve-t z za zb)
(/ (- z za) (- zb za)))
(define-syntax-rule (unsafe-solve-t z za zb)
(unsafe-fl/ (unsafe-fl- z za) (unsafe-fl- zb za)))
(define-syntax-rule (unsafe-unsolve-t za zb t)
(unsafe-fl+ (unsafe-fl* t zb) (unsafe-fl* (unsafe-fl- 1.0 t) za)))
(define-syntax-rule (unsolve-t za zb t)
(cond [(eq? t 0) za]
[(eq? t 1) zb]
[else (+ (* t zb) (* (- 1 t) za))]))
(define-syntax-rule (unsafe-flavg4 z1 z2 z3 z4)
(unsafe-fl* 0.25 (unsafe-fl+ (unsafe-fl+ (unsafe-fl+ z1 z2) z3) z4)))
(define-syntax-rule (all pred? obj ...) (and (pred? obj) ...))
(define-syntax (find-failure-index stx)
(syntax-case stx ()
[(_ pred? id ...)
(with-syntax ([(i ...) (build-list (length (syntax->list #'(id ...))) values)])
(syntax/loc stx
(or (and (not (pred? id)) i) ...)))]))
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