- float x, y, exp_x, scale1, scale2;
- int ex_expt, half_expt;
-
- x = crealf(z);
- y = cimagf(z);
- exp_x = __frexp_expf(x, &ex_expt);
- expt += ex_expt;
-
- half_expt = expt / 2;
- SET_FLOAT_WORD(scale1, (0x7f + half_expt) << 23);
- half_expt = expt - half_expt;
- SET_FLOAT_WORD(scale2, (0x7f + half_expt) << 23);
-
- return (cpackf(cosf(y) * exp_x * scale1 * scale2,
- sinf(y) * exp_x * scale1 * scale2));
+ float scale;
+ int n;
+
+ /*
+ * efficient scalbnf(y, k-1):
+ * 2**(k-1) cannot be represented
+ * so we use that k-1 is even and scale in two steps
+ */
+ n = (k - 1)/2;
+ SET_FLOAT_WORD(scale, (0x7f + n) << 23);
+ return expf(x - kln2) * scale * scale;