bpo-41513: Improve order of adding fractional values. Improve variable names. (GH-22368)
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@ -2502,8 +2502,8 @@ References:
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static inline double
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vector_norm(Py_ssize_t n, double *vec, double max, int found_nan)
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{
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const double T27 = 134217729.0; /* ldexp(1.0, 27)+1.0) */
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double x, csum = 1.0, oldcsum, scale, frac=0.0, frac_mid=0.0, frac_lo=0.0;
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const double T27 = 134217729.0; /* ldexp(1.0, 27) + 1.0) */
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double x, scale, oldcsum, csum = 1.0, frac1 = 0.0, frac2 = 0.0, frac3 = 0.0;
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double t, hi, lo, h;
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int max_e;
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Py_ssize_t i;
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@ -2539,18 +2539,18 @@ vector_norm(Py_ssize_t n, double *vec, double max, int found_nan)
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assert(fabs(csum) >= fabs(x));
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oldcsum = csum;
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csum += x;
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frac += (oldcsum - csum) + x;
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frac1 += (oldcsum - csum) + x;
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x = 2.0 * hi * lo;
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assert(fabs(csum) >= fabs(x));
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oldcsum = csum;
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csum += x;
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frac_mid += (oldcsum - csum) + x;
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frac2 += (oldcsum - csum) + x;
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assert(csum + lo * lo == csum);
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frac_lo += lo * lo;
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frac3 += lo * lo;
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}
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h = sqrt(csum - 1.0 + (frac_lo + frac_mid + frac));
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h = sqrt(csum - 1.0 + (frac1 + frac2 + frac3));
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x = h;
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t = x * T27;
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@ -2562,21 +2562,21 @@ vector_norm(Py_ssize_t n, double *vec, double max, int found_nan)
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assert(fabs(csum) >= fabs(x));
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oldcsum = csum;
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csum += x;
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frac += (oldcsum - csum) + x;
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frac1 += (oldcsum - csum) + x;
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x = -2.0 * hi * lo;
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assert(fabs(csum) >= fabs(x));
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oldcsum = csum;
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csum += x;
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frac_mid += (oldcsum - csum) + x;
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frac2 += (oldcsum - csum) + x;
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x = -lo * lo;
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assert(fabs(csum) >= fabs(x));
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oldcsum = csum;
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csum += x;
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frac_lo += (oldcsum - csum) + x;
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frac3 += (oldcsum - csum) + x;
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x = csum - 1.0 + (frac_lo + frac_mid + frac);
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x = csum - 1.0 + (frac1 + frac2 + frac3);
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return (h + x / (2.0 * h)) / scale;
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}
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/* When max_e < -1023, ldexp(1.0, -max_e) overflows.
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@ -2591,9 +2591,9 @@ vector_norm(Py_ssize_t n, double *vec, double max, int found_nan)
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assert(fabs(csum) >= fabs(x));
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oldcsum = csum;
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csum += x;
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frac += (oldcsum - csum) + x;
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frac1 += (oldcsum - csum) + x;
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}
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return max * sqrt(csum - 1.0 + frac);
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return max * sqrt(csum - 1.0 + frac1);
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}
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#define NUM_STACK_ELEMS 16
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