What's wrong with the user parameterizing it like this? To save you from
having to read the whole thing, it randomly makes digits that belong to
either the integer or fractional portion where the user chooses the max
number of digits to generate.
;ms = max sig fig count, rs = rand sig fig count
There's a random-real generator in
math/private/utils/flonum-tests.rkt. The generator Typed Racket uses
is in tests/typed-racket/random-real.rkt.
I haven't settled on a general-purpose real number generator. For
flonums I usually write something like this:
#lang racket
(require math/base
Thanks, Neil!
Why is the loop needed? I can't seem to get it to take more than one iteration.
Robby
On Mon, May 12, 2014 at 11:24 PM, Neil Toronto neil.toro...@gmail.com wrote:
He went with exact rationals. Here's another option, which preserves
inexactness:
(define (angle-proper-range
I can't get it to take more than on iteration, either. It's there in
case I missed something. :)
Neil ⊥
On 05/13/2014 05:59 AM, Robby Findler wrote:
Thanks, Neil!
Why is the loop needed? I can't seem to get it to take more than one iteration.
Robby
On Mon, May 12, 2014 at 11:24 PM, Neil
Okay, then I'll go with this:
(define/contract (angle-proper-range α)
(- real? (between/c 0 360))
(let loop ([θ (- α (* 360 (floor (/ α 360])
(cond [(negative? θ) (+ θ 360)]
[(= θ 360)(- θ 360)]
[else θ])))
Can you point me to your random real number
Hello all,
I can't figure this out as I have no function called degrees-complex and
it occurs only sometimes. It's always when rotating stuff through the
positive x axis, as in it's probably related to floating point operations
like sin or cos near 0 or perhaps integer multiples of 2pi. So far
On Mon, May 12, 2014 at 4:11 PM, Sean Kanaley skana...@gmail.com wrote:
Hello all,
I can't figure this out as I have no function called degrees-complex and it
occurs only sometimes. It's always when rotating stuff through the positive
x axis, as in it's probably related to floating point
Hi Sean: do you have a program that demonstrates this error that you can
share? That'll let me track down the bug.
Hi Danny: The contracts are checked at the boundary based on the define/chk
macro. This is an internal error somewhere -- angles are not restricted to
being between 0 and 360. I
Hi Danny: The contracts are checked at the boundary based on the
define/chk macro. This is an internal error somewhere -- angles are not
restricted to being between 0 and 360. I don't suppose you noticed how to
make this error happen?
Apologies; I didn't have time to investigate a good test
No no, not at all! Leads are also welcome. The obvious things I tried
didn't signal an error.
Robby
On Mon, May 12, 2014 at 9:04 PM, Danny Yoo d...@hashcollision.org wrote:
Hi Danny: The contracts are checked at the boundary based on the
define/chk macro. This is an internal error somewhere
The entire program is too big but some tests:
pass ... (rotate -0.0 SHIP)
pass ... (rotate -0.0001 SHIP)
fail... (rotate -0.0001 SHIP)
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http://lists.racket-lang.org/users
Thanks! I've pushed a fix.
Robby
On Mon, May 12, 2014 at 9:19 PM, Sean Kanaley skana...@gmail.com wrote:
The entire program is too big but some tests:
pass ... (rotate -0.0 SHIP)
pass ... (rotate -0.0001 SHIP)
fail... (rotate -0.0001 SHIP)
Wow. Floating point really is nasty. I see how it might have happened now.
;;;
-0.0001
-1e-16
(+ 360 -1e-16)
360.0
;;;
Racket Users list:
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Right. Probably there is a better fix, but the essential problem, as I
understand it, is that there are more floating points between 0 and 1
than between any two other integers and the code made the assumption
that that didn't happen
The basic desire is to turn a real number into a number in
Interesting, my code has the same bug then. I called it modulo/real, used
for things like displaying the space ship's rotation to the user or
wrapping x coordinates to stay in the world. Apparently it's going to fail
at some point with vector ref out of range. What was your fix? I was
thinking
He went with exact rationals. Here's another option, which preserves
inexactness:
(define (angle-proper-range α)
(let loop ([θ (- α (* 360 (floor (/ α 360])
(cond [(negative? θ) (loop (+ θ 360))]
[(= θ 360) (loop (- θ 360))]
[else θ])))
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