Re: [go-nuts] Mathematical operations - the generics way
I don't know if it's important to you, but your Max[float64] isn't
compatible with math.Max in the standard library.
For example, Max[float64](NaN, 1) returns 1 rather than NaN.
On Tuesday, 22 March 2022 at 16:58:40 UTC+1 esi...@gmail.com wrote:
> I found a working version meantime.
>
> // Max returns the bigger value between two numbers.
> func Max[T constraints.Ordered](x, y T) T {
> if x > y {
> return x
> }
> return y
> }
>
> // Abs returns the absolut value of x.
> func Abs[T constraints.Signed | constraints.Float](x T) T {
> if x < 0 {
> return -x
> }
> return x
> }
>
> On Saturday, March 19, 2022 at 12:22:39 PM UTC+2 Gergely Födémesi wrote:
>
>> some details: https://github.com/golang/go/issues/48918
>>
>> On 3/18/22, Endre Simo wrote:
>> > Now that generics are officially supported, I was checking in the Go
>> source
>> >
>> > if there are some generic implementation of utility methods like Abs,
>> Min,
>> > Max etc, but I couldn't find it other than this
>> > proposal https://github.com/golang/go/discussions/48287.
>> >
>> > Anyone knows if something related has been adopted and implemented in
>> Go
>> > 1.18?
>> >
>> > --
>> > You received this message because you are subscribed to the Google
>> Groups
>> > "golang-nuts" group.
>> > To unsubscribe from this group and stop receiving emails from it, send
>> an
>> > email to golang-nuts...@googlegroups.com.
>> > To view this discussion on the web visit
>> >
>> https://groups.google.com/d/msgid/golang-nuts/e930b89a-0ba6-46f5-b3ec-7aeb26d8acf9n%40googlegroups.com.
>>
>>
>> >
>>
>
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[go-nuts] Re: modules and my v2 package only partly appearing on go.dev
On Friday, 28 February 2020 20:43:16 UTC+1, Paul Hankin wrote: > > I am rather confused about modules, and have trouble making them work. > > I have a package: https://github.com/paulhankin/poker > > The go.mod looks like this: ` > module github.com/paulhankin/poker/v2 > > go 1.13 > ` > > The package has a v1, and v2. At v2, I moved the main part of the package > into a subdirectory "poker" so the import would be " > github.com/paulhankin/poker/v2/poker" rather than " > github.com/paulhankin/poker/v2". > > I can successfully import the v2 package in a new modules-aware project, > and goproxy seems to pick up new versions: > > $ go list -m --versions > github.com/paulhankin/poker/v2 v2.0.0 v2.0.2 v2.0.3 v2.0.4 v2.0.5 v2.0.6 > v2.0.7 > > > I can't find the documentation on go.dev though. The closest I can find > is this: > https://pkg.go.dev/github.com/paulhankin/poker/v2 > which contains the cmd subdirectory, but not the poker subdirectory. > > Am I doing something wrong? Did I make a mistake in moving the package > into a subdirectory, or is there an easier way to avoid the import name > being "v2"? > > I'd file a bug against go.dev if I thought it was broken, but I find > modules so complicated that I don't know if it's my understanding that's > wrong, or if I made a mistake, or if go.dev isn't working correctly. I'm > pretty frustrated with the experience so far. > Just to finish up here, go.dev now contains the documentation for the package. I guess I had to wait for the v2.0.0 version to disappear from some cache. -- Paul Hankin -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/6d2efc59-4f51-4a24-848a-416a3866c5c1%40googlegroups.com.
[go-nuts] Re: modules and my v2 package only partly appearing on go.dev
On Friday, 28 February 2020 21:04:04 UTC+1, Paul Hankin wrote: > > On Friday, 28 February 2020 20:43:16 UTC+1, Paul Hankin wrote: >> >> I am rather confused about modules, and have trouble making them work. >> >> I have a package: https://github.com/paulhankin/poker >> >> The go.mod looks like this: ` >> module github.com/paulhankin/poker/v2 >> >> go 1.13 >> ` >> >> The package has a v1, and v2. At v2, I moved the main part of the package >> into a subdirectory "poker" so the import would be " >> github.com/paulhankin/poker/v2/poker" rather than " >> github.com/paulhankin/poker/v2". >> >> I can successfully import the v2 package in a new modules-aware project, >> and goproxy seems to pick up new versions: >> >> $ go list -m --versions >> github.com/paulhankin/poker/v2 v2.0.0 v2.0.2 v2.0.3 v2.0.4 v2.0.5 v2.0.6 >> v2.0.7 >> >> >> I can't find the documentation on go.dev though. The closest I can find >> is this: >> https://pkg.go.dev/github.com/paulhankin/poker/v2 >> which contains the cmd subdirectory, but not the poker subdirectory. >> >> Am I doing something wrong? Did I make a mistake in moving the package >> into a subdirectory, or is there an easier way to avoid the import name >> being "v2"? >> >> I'd file a bug against go.dev if I thought it was broken, but I find >> modules so complicated that I don't know if it's my understanding that's >> wrong, or if I made a mistake, or if go.dev isn't working correctly. I'm >> pretty frustrated with the experience so far. >> > > Oh, I see the problem. I created the subdirectory after tagging v2.0.0. > I deleted the tag, and go.dev has removed the v2.0.0 release, but the package /poker is still not showing up on https://pkg.go.dev/mod/github.com/paulhankin/poker/v2?tab=packages Can someone please help? -- Paul Hankin -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/c1ecf162-dd8e-4262-9a66-3c400dcafd60%40googlegroups.com.
[go-nuts] Re: modules and my v2 package only partly appearing on go.dev
On Friday, 28 February 2020 20:43:16 UTC+1, Paul Hankin wrote: > > I am rather confused about modules, and have trouble making them work. > > I have a package: https://github.com/paulhankin/poker > > The go.mod looks like this: ` > module github.com/paulhankin/poker/v2 > > go 1.13 > ` > > The package has a v1, and v2. At v2, I moved the main part of the package > into a subdirectory "poker" so the import would be " > github.com/paulhankin/poker/v2/poker" rather than " > github.com/paulhankin/poker/v2". > > I can successfully import the v2 package in a new modules-aware project, > and goproxy seems to pick up new versions: > > $ go list -m --versions > github.com/paulhankin/poker/v2 v2.0.0 v2.0.2 v2.0.3 v2.0.4 v2.0.5 v2.0.6 > v2.0.7 > > > I can't find the documentation on go.dev though. The closest I can find > is this: > https://pkg.go.dev/github.com/paulhankin/poker/v2 > which contains the cmd subdirectory, but not the poker subdirectory. > > Am I doing something wrong? Did I make a mistake in moving the package > into a subdirectory, or is there an easier way to avoid the import name > being "v2"? > > I'd file a bug against go.dev if I thought it was broken, but I find > modules so complicated that I don't know if it's my understanding that's > wrong, or if I made a mistake, or if go.dev isn't working correctly. I'm > pretty frustrated with the experience so far. > Oh, I see the problem. I created the subdirectory after tagging v2.0.0. -- Paul Hankin -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/21888ea2-b3a6-4340-adaa-2d8f9c07402e%40googlegroups.com.
[go-nuts] modules and my v2 package only partly appearing on go.dev
I am rather confused about modules, and have trouble making them work. I have a package: https://github.com/paulhankin/poker The go.mod looks like this: ` module github.com/paulhankin/poker/v2 go 1.13 ` The package has a v1, and v2. At v2, I moved the main part of the package into a subdirectory "poker" so the import would be "github.com/paulhankin/poker/v2/poker" rather than "github.com/paulhankin/poker/v2". I can successfully import the v2 package in a new modules-aware project, and goproxy seems to pick up new versions: $ go list -m --versions github.com/paulhankin/poker/v2 v2.0.0 v2.0.2 v2.0.3 v2.0.4 v2.0.5 v2.0.6 v2.0.7 I can't find the documentation on go.dev though. The closest I can find is this: https://pkg.go.dev/github.com/paulhankin/poker/v2 which contains the cmd subdirectory, but not the poker subdirectory. Am I doing something wrong? Did I make a mistake in moving the package into a subdirectory, or is there an easier way to avoid the import name being "v2"? I'd file a bug against go.dev if I thought it was broken, but I find modules so complicated that I don't know if it's my understanding that's wrong, or if I made a mistake, or if go.dev isn't working correctly. I'm pretty frustrated with the experience so far. Thanks, Paul Hankin -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/44b8db77-42fd-42cb-8dcc-8788c3d0e69b%40googlegroups.com.
Re: [go-nuts] float accuracy when calculating Fibonacci numbers
On Friday, 27 April 2018 23:57:42 UTC+2, Michael Jones wrote: > > Yuval, > > There are fundamental issues here. > > 1. That equation (de Moivre, Binet) is from the algebra of ideal numbers. > Numbers of infinite precision. Not the realm of computer arithmetic. It > works fine with double precision (go: float64, c/c++: double) up to F(75) > but must fail for F(76) due to the limited precision of 64-bit floating > point and has nothing to do with language. > > F(76) = 3416454622906707 but the best we can do in 64 bits is > 3416454622906706 even with a Pow() function good to +/-1 least significant > bit. > > 2. Another difference between algebra and computer arithmetic > (well...actually about the floor function) is that one of your two power > terms is not needed. Psi < 1 so Psi^N is pretty small, so small, that it > never changes the value of the rounded result. So you can just evaluate: > > return round(math.Pow(math.Phi, float_n) / sqrt_5) > A neat not-very-well-known trick is to use that phi^n = Fib(n)phi + Fib(n-1). Numbers of the form a*phi+b where a and b are integers are closed under multiplication, so you can compute phi^n exactly using integer arithmetic -- in log(n) arithmetic operations. https://play.golang.org/p/j4mZ93c820R -- Paul -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[go-nuts] Re: constant 256 overflows byte
On Tuesday, 7 March 2017 19:02:59 UTC-5, Eric Brown wrote: > > memoryBlock := make([]byte, 4) > > binary.LittleEndian.PutUint32(memoryBlock, 12345678) > > > > memoryBlock[2] = 256 - (187 - memoryBlock[2]) ' results in error: > constant 256 overflows byte > memoryBlock[2] = 255 - (187 - memoryBlock[2]) + 1 ' results in no errors > > > Why is this, and what would be your suggested method of handling this? > I don't like having to do the later as it just looks sloppy. > > Byte operations work modulo 256, so adding 256 does nothing. Using that, you can simplify your expression to this: memoryBlock[2] -= 187 https://play.golang.org/p/5ljs4wIeq9 -- Paul Hankin -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
