[bug #26809] Some common math constants missing in math.h

[Mario Castelán Castro]

URL:
  <http://savannah.nongnu.org/bugs/?26809>

                 Summary: Some common math constants missing in math.h
                 Project: AVR C Runtime Library
            Submitted by: ganzziani
            Submitted on: Mon 15 Jun 2009 01:11:52 PM GMT
                Category: Header
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Header files
                  Status: None
        Percent Complete: 0%
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 1.6.6
           Fixed Release: None

    _______________________________________________________

Details:

Only M_PI and M_SQRT2 are defined in math.h, but all these should be
defined:

#define M_E 2.7182818284590452354 /* e */
#define M_LOG2E 1.4426950408889634074 /* log 2e */
#define M_LOG10E 0.43429448190325182765 /* log 10e */
#define M_LN2 0.69314718055994530942 /* log e2 */
#define M_LN10 2.30258509299404568402 /* log e10 */
#define M_PI 3.14159265358979323846 /* pi */
#define M_PI_2 1.57079632679489661923 /* pi/2 */
#define M_PI_4 0.78539816339744830962 /* pi/4 */
#define M_1_PI 0.31830988618379067154 /* 1/pi */
#define M_2_PI 0.63661977236758134308 /* 2/pi */
#define M_2_SQRTPI 1.12837916709551257390 /* 2/sqrt(pi) */
#define M_SQRT2 1.41421356237309504880 /* sqrt(2) */
#define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */




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[Stu Bell]

> #define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */

While I have no problem with the constant, shouldn't the symbol name be
M_1_SQRT2?  That would follow the naming set up by M_1_PI and M_2_PI and
. . .

Best regards,

Stu Bell
DataPlay (DPHI, Inc.)

 

> #define M_E 2.7182818284590452354 /* e */
> #define M_LOG2E 1.4426950408889634074 /* log 2e */
> #define M_LOG10E 0.43429448190325182765 /* log 10e */
> #define M_LN2 0.69314718055994530942 /* log e2 */
> #define M_LN10 2.30258509299404568402 /* log e10 */
> #define M_PI 3.14159265358979323846 /* pi */
> #define M_PI_2 1.57079632679489661923 /* pi/2 */
> #define M_PI_4 0.78539816339744830962 /* pi/4 */
> #define M_1_PI 0.31830988618379067154 /* 1/pi */
> #define M_2_PI 0.63661977236758134308 /* 2/pi */
> #define M_2_SQRTPI 1.12837916709551257390 /* 2/sqrt(pi) */
> #define M_SQRT2 1.41421356237309504880 /* sqrt(2) */

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[Stu Bell]

> > #define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */
>
> While I have no problem with the constant, shouldn't the
> symbol name be M_1_SQRT2?  That would follow the naming set
> up by M_1_PI and M_2_PI and . . .

Please ignore my brain fart.  Obviously 1/sqrt(2) = sqrt(1/2).  My bad.

(In my defense, it was a *long* weekend for me.  ;-) )

Stu


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[Mario Castelán Castro]

Update of bug #26809 (project avr-libc):

             Assigned to:                    None => dmix                  

    _______________________________________________________

Follow-up Comment #1:

In general, agree.
But I am not shure about the necessity of macroses like M_PI_2: the Avr-gcc
precalculates the constant expressions regardless of optimization level.
(Note, the C99 standart does not demand any math constants.)


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[Mario Castelán Castro]

Update of bug #26809 (project avr-libc):

                  Status:                    None => Fixed                  
        Percent Complete:                      0% => 100%                  
             Open/Closed:                    Open => Closed                

    _______________________________________________________

Follow-up Comment #2:

A set of constants (from Glibc) is added to 1_6 and HEAD branches.


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