Re: How to generate a random number from system clock as seed
On Saturday, 8 June 2024 at 20:53:02 UTC, Nick Treleaven wrote: On Saturday, 8 June 2024 at 16:09:04 UTC, monkyyy wrote: rng is an optional parameter, `uniform(0,100).writeln;` alone works; the docs not telling you that is really bad They do tell you: urng (optional) random number generator to use; if not specified, defaults to rndGen That overload is used in the 2nd example. https://dlang.org/phobos/std_random.html#.uniform generate is a very rare function and do novices understand lamdas?
Re: How to generate a random number from system clock as seed
On Saturday, 8 June 2024 at 16:09:04 UTC, monkyyy wrote: rng is an optional parameter, `uniform(0,100).writeln;` alone works; the docs not telling you that is really bad They do tell you: urng (optional) random number generator to use; if not specified, defaults to rndGen That overload is used in the 2nd example. https://dlang.org/phobos/std_random.html#.uniform
Re: How to generate a random number from system clock as seed
On Saturday, 8 June 2024 at 18:25:20 UTC, drug007 wrote:
```d
{
const seed = castFrom!long.to!uint(Clock.currStdTime);
auto rng = Random(seed);
auto result = generate!(() => uniform(0, 10,
rng))().take(7);
// new random numbers sequence every time
result.writeln;
}
```
If UnixTime is desired, it is sufficient to have
currTime.toUnixTime instead of currStdTime. It will not reset
until January 19, 2038.
```d
auto seed = to!uint(Clock.currTime.toUnixTime);
```
SDB@79
Re: How to generate a random number from system clock as seed
On 08.06.2024 16:19, Eric P626 wrote:
I managed to create a random number generator using the following code:
~~~
auto rng = Random(42);
//
uniform(0,10,rng);
~~~
Now I want to seed the generator using system time. I looked at Date &
time functions/classes and systime functions/classes. The problem is
that they all require a time zone. But I don't need a time zone since
there is no time zone. I just want the number of seconds elapsed since
jan 1st 1970. In other words, the internal system clock value.
```d
import std;
void main()
{
{
auto rng = Random(42);
auto result = generate!(() => uniform(0, 10, rng))().take(7);
// the same random numbers sequence
assert (result.equal([2, 7, 6, 4, 6, 5, 0]));
}
{
const seed = castFrom!long.to!uint(Clock.currStdTime);
auto rng = Random(seed);
auto result = generate!(() => uniform(0, 10, rng))().take(7);
// new random numbers sequence every time
result.writeln;
}
}
```
Re: How to generate a random number from system clock as seed
On Saturday, 8 June 2024 at 13:19:30 UTC, Eric P626 wrote: I managed to create a random number generator using the following code: ~~~ auto rng = Random(42); // uniform(0,10,rng); ~~~ Now I want to seed the generator using system time. I looked at Date & time functions/classes and systime functions/classes. The problem is that they all require a time zone. But I don't need a time zone since there is no time zone. I just want the number of seconds elapsed since jan 1st 1970. In other words, the internal system clock value. rng is an optional parameter, `uniform(0,100).writeln;` alone works; the docs not telling you that is really bad the docs/api for std.time/random are bad if you need something specif Id suggest doing it yourself, but if you want to use std.time anyway the magic word I think is "localtime"(Ive pounded my head into those auto generated docs and had to dive deep to find such estoric knowledge) if you need a spefic random number from a spefic timestamp, Id suggest making a rng function from scratch and using clibs time stuff
Re: How to generate a random number from system clock as seed
On Saturday, 8 June 2024 at 13:19:30 UTC, Eric P626 wrote: I just want the number of seconds elapsed since jan 1st 1970. In other words, the internal system clock value. #unix #time @SDB79
How to generate a random number from system clock as seed
I managed to create a random number generator using the following code: ~~~ auto rng = Random(42); // uniform(0,10,rng); ~~~ Now I want to seed the generator using system time. I looked at Date & time functions/classes and systime functions/classes. The problem is that they all require a time zone. But I don't need a time zone since there is no time zone. I just want the number of seconds elapsed since jan 1st 1970. In other words, the internal system clock value.
Re: modInverse & powMod
On Friday, 7 June 2024 at 13:43:29 UTC, Salih Dincer wrote:
SDB@79
I have only one question: Is there a modInverse() function in
the standard library for use in RSA?
Apparently not, it fell to lot :)
I already had such a function...
```d
auto modInverse(T)(T m, T n) pure
{
T q, ilk = n;
T y, tmp, x = 1;
while (m > 1)
{
q = m / n;
tmp = n;
n = m % n;
m = tmp;
tmp = y;
y = x - q * y;
x = tmp;
}
return x < 0 ? x + ilk : x;
}
```
And in the BigInt module there was divMod() next to powmod():
```d
auto modInverse(BigInt a, BigInt m)
{
BigInt q, m0 = m;
BigInt tmp, y, x = 1;
while (a > 1)
{
// m is remainder now
tmp = m;
divMod(a, m, q, m);
// process same as Euclid's algorithm
a = tmp;
tmp = y;
// Update y and x
y = x - q * y;
x = tmp;
}
// Make x positive
if (x < 0) x += m0;
return x;
}
```
Is PR required? Why not modInverse too!
SDB@79
Re: How do I install a non-outdated D compiler on Linux? (not in userspace-container)
On Saturday, 8 June 2024 at 03:36:05 UTC, bachmeier wrote: For Mint, I'd use the .deb and let it handle that stuff. For LDC, I have a bash alias for ldmd2 that points to the ldmd2 binary. Of course there are multiple ways to handle this, but I don't understand the point of the install script, since it leaves you without a working installation. Okay, does someone know how to set up the path for LDC on Linux, without the bash alias?
Re: Trying to call some C code using Extern(C) but got unexpected linker error
On Saturday, 8 June 2024 at 02:22:00 UTC, Xiaochao Yan wrote:
Hi, I am new to D and is experimenting with game development
using D and C.
I had some problem when trying to recreate the
https://dlang.org/spec/importc.html
[...]
Thanks in advance!
on a recent compiler this should work:
```d
// .d file
import std.stdio;
import std.conv;
import test;
void main() {
writeln("Hello, World!");
pragma(mangle, "printMessage");
extern (C) void printMessage();
printMessage();
}
```
This was fixed by the dear GH Ghost in
https://github.com/dlang/dmd/pull/15582.
A short technical explanation: mangling and call conventions are
not 100% related.
You need to stuff the mangle for that to work.
