Hough transform/Racket: Difference between revisions

{{trans|C}}

 

===Hough-transform-basic.rkt===

 

;;; Note that types are not mentioned here at all in this package

 

[(exn? (λ (x) (place-channel-put ch (cons name (exn-message x)))))]

(sub-hough-transform-channel w h trg-pxls trg-h deg-start deg-end chnl-pxls)

 

===Hough-transform-fast.rkt===

Note the block:

 

(require (filtered-in

(λ (name) (regexp-replace #rx"unsafe-" name ""))

racket/unsafe/ops))

 

This uses unsafe, but fast, versions of <code>fx...</code> and <code>fl...</code> functions. If (especially during development and testing), one of these functions receives a non-{fix,flo}num value, then you could lose your interpreter... even DrRacket won't save you. 'Unsafe' means 'unsafe'! So until you are confident use:

 

#;(require (filtered-in

(λ (name) (regexp-replace #rx"unsafe-" name ""))

racket/unsafe/ops))

 

Racket type checks and raises exceptions against <code>fx...</code> and <code>fl...</code> functions. Once these are purged, you can remove your safety harness!

 

 

;;; This module tries to be a little smarter about types. It *should* prove to be better performing

[(exn? (λ (x) (place-channel-put ch (cons name (exn-message x)))))]

(sub-hough-transform-channel w h trg-pxls trg-h deg-start deg-end chnl-pxls)

 

===Hough-transform.rkt===

(define (sub-hough-transform-channel w h trg-pxls trg-h deg-start deg-end chnl-pxls) ...)

 

;;; Derived from a port of TCL (hence the colouring of the output)

 

(transform-image "180px-Pentagon.png" "Hough-transform-basic.rkt")

(transform-image "180px-Pentagon.png" "Hough-transform-fast.rkt")