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Annotation of coherent/b/lib/libm/log10.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Evaluate the logarithm (base 10) function.
        !             3:  * (Hart 2355, 19.74)
        !             4:  */
        !             5: #include <math.h>
        !             6: 
        !             7: #if    EMU87
        !             8: #include "emumath.h"
        !             9: #endif
        !            10: 
        !            11: static readonly double logntab[] ={
        !            12:        -0.1042911213725266949744122e+02,
        !            13:         0.1344458152275036223645300e+02,
        !            14:        -0.4185596001312662063300000e+01,
        !            15:         0.1828759212091999337000000e+00
        !            16: };
        !            17: static readonly double logmtab[] ={
        !            18:        -0.1200695907020063424342180e+02,
        !            19:         0.1948096618798093652415500e+02,
        !            20:        -0.8911109060902708565400000e+01,
        !            21:         0.1000000000000000000000000e+01
        !            22: };
        !            23: 
        !            24: double
        !            25: log10(x)
        !            26: double x;
        !            27: {
        !            28:        double r, z;
        !            29:        int n;
        !            30: 
        !            31:        if (x <= 0.0) {
        !            32:                errno = EDOM;
        !            33:                return (0.0);
        !            34:        }
        !            35:        if (x == 1.)
        !            36:                return(0.);
        !            37:        x = frexp(x, &n);
        !            38:        x *= SQRT2;
        !            39:        z = (x-1.0)/(x+1.0);
        !            40:        r = z*z;
        !            41:        r = z*(_pol(r, logntab, 4)/_pol(r, logmtab, 4));
        !            42:        r += (n-0.5)*LOG2B10;
        !            43:        return (r);
        !            44: }

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