Skip to content

[ltsmaster] Porting: gammafunction: Add constants for ieeeQuadruple r… #52

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
redstar merged 1 commit into from
Feb 20, 2018
Merged

[ltsmaster] Porting: gammafunction: Add constants for ieeeQuadruple r… #52

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
31 changes: 28 additions & 3 deletions std/internal/math/gammafunction.d
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -243,7 +243,9 @@ real igammaTemmeLarge(real a, real x)

public:
/// The maximum value of x for which gamma(x) < real.infinity.
static if (floatTraits!(real).realFormat == RealFormat.ieeeExtended)
static if (floatTraits!(real).realFormat == RealFormat.ieeeQuadruple)
enum real MAXGAMMA = 1755.5483429L;
else static if (floatTraits!(real).realFormat == RealFormat.ieeeExtended)
enum real MAXGAMMA = 1755.5483429L;
else static if (floatTraits!(real).realFormat == RealFormat.ieeeDouble)
enum real MAXGAMMA = 171.6243769L;
Expand Down Expand Up @@ -553,11 +555,34 @@ unittest {


private {
static if (floatTraits!(real).realFormat == RealFormat.ieeeExtended) {
/*
* These value can be calculated like this:
* 1) Get exact real.max/min_normal/epsilon from compiler:
* writefln!"%a"(real.max/min_normal_epsilon)
* 2) Convert for Wolfram Alpha
* 0xf.fffffffffffffffp+16380 ==> (f.fffffffffffffff base 16) * 2^16380
* 3) Calculate result on wofram alpha:
* http://www.wolframalpha.com/input/?i=ln((1.ffffffffffffffffffffffffffff+base+16)+*+2%5E16383)+in+base+2
* 4) Convert to proper format:
* string mantissa = "1.011...";
* write(mantissa[0 .. 2]); mantissa = mantissa[2 .. $];
* for (size_t i = 0; i < mantissa.length/4; i++)
* {
* writef!"%x"(to!ubyte(mantissa[0 .. 4], 2)); mantissa = mantissa[4 .. $];
* }
*/
static if (floatTraits!(real).realFormat == RealFormat.ieeeQuadruple)
{
enum real MAXLOG = 0x1.62e42fefa39ef35793c7673007e6p+13; // log(real.max)
enum real MINLOG = -0x1.6546282207802c89d24d65e96274p+13; // log(real.min_normal*real.epsilon) = log(smallest denormal)
}
else static if (floatTraits!(real).realFormat == RealFormat.ieeeExtended)
{
enum real MAXLOG = 0x1.62e42fefa39ef358p+13L; // log(real.max)
enum real MINLOG = -0x1.6436716d5406e6d8p+13L; // log(real.min_normal*real.epsilon) = log(smallest denormal)
}
else static if (floatTraits!(real).realFormat == RealFormat.ieeeDouble) {
else static if (floatTraits!(real).realFormat == RealFormat.ieeeDouble)
{
enum real MAXLOG = 0x1.62e42fefa39efp+9L; // log(real.max)
enum real MINLOG = -0x1.74385446d71c3p+9L; // log(real.min_normal*real.epsilon) = log(smallest denormal)
}
Expand Down