1 files changed, 40 insertions, 0 deletions
diff --git a/modules/fdlibm/patches/17_exp_exact_result_for_positive_one.patch b/modules/fdlibm/patches/17_exp_exact_result_for_positive_one.patch
new file mode 100644
index 0000000000..ada59b23a2
--- /dev/null
+++ b/modules/fdlibm/patches/17_exp_exact_result_for_positive_one.patch
@@ -0,0 +1,40 @@
+diff --git a/e_exp.cpp b/e_exp.cpp
+--- a/e_exp.cpp
++++ b/e_exp.cpp
+@@ -91,16 +91,18 @@ ln2LO[2]   ={ 1.90821492927058770002e-10,  /* 0x3dea39ef, 0x35793c76 */
+ 	     -1.90821492927058770002e-10,},/* 0xbdea39ef, 0x35793c76 */
+ invln2 =  1.44269504088896338700e+00, /* 0x3ff71547, 0x652b82fe */
+ P1   =  1.66666666666666019037e-01, /* 0x3FC55555, 0x5555553E */
+ P2   = -2.77777777770155933842e-03, /* 0xBF66C16C, 0x16BEBD93 */
+ P3   =  6.61375632143793436117e-05, /* 0x3F11566A, 0xAF25DE2C */
+ P4   = -1.65339022054652515390e-06, /* 0xBEBBBD41, 0xC5D26BF1 */
+ P5   =  4.13813679705723846039e-08; /* 0x3E663769, 0x72BEA4D0 */
+ 
++static const double E = 2.7182818284590452354;	/* e */
++
+ static volatile double
+ huge	= 1.0e+300,
+ twom1000= 9.33263618503218878990e-302;     /* 2**-1000=0x01700000,0*/
+ 
+ double
+ __ieee754_exp(double x)	/* default IEEE double exp */
+ {
+ 	double y,hi=0.0,lo=0.0,c,t,twopk;
+@@ -122,16 +124,17 @@ __ieee754_exp(double x)	/* default IEEE double exp */
+ 	    }
+ 	    if(x > o_threshold) return huge*huge; /* overflow */
+ 	    if(x < u_threshold) return twom1000*twom1000; /* underflow */
+ 	}
+ 
+     /* argument reduction */
+ 	if(hx > 0x3fd62e42) {		/* if  |x| > 0.5 ln2 */ 
+ 	    if(hx < 0x3FF0A2B2) {	/* and |x| < 1.5 ln2 */
++		if (x == 1.0) return E;
+ 		hi = x-ln2HI[xsb]; lo=ln2LO[xsb]; k = 1-xsb-xsb;
+ 	    } else {
+ 		k  = (int)(invln2*x+halF[xsb]);
+ 		t  = k;
+ 		hi = x - t*ln2HI[0];	/* t*ln2HI is exact here */
+ 		lo = t*ln2LO[0];
+ 	    }
+ 	    STRICT_ASSIGN(double, x, hi - lo);