\[1 - \left(\frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(1.42141374100000006 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-1.45315202700000001 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot 1.0614054289999999\right)\right)\right)\right)\right) \cdot e^{-\left|x\right| \cdot \left|x\right|}\]

1 - \left(\frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(1.42141374100000006 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-1.45315202700000001 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot 1.0614054289999999\right)\right)\right)\right)\right) \cdot e^{-\left|x\right| \cdot \left|x\right|}

double f(double x) {
        double r41972 = 1.0;
        double r41973 = 0.3275911;
        double r41974 = x;
        double r41975 = fabs(r41974);
        double r41976 = r41973 * r41975;
        double r41977 = r41972 + r41976;
        double r41978 = r41972 / r41977;
        double r41979 = 0.254829592;
        double r41980 = -0.284496736;
        double r41981 = 1.421413741;
        double r41982 = -1.453152027;
        double r41983 = 1.061405429;
        double r41984 = r41978 * r41983;
        double r41985 = r41982 + r41984;
        double r41986 = r41978 * r41985;
        double r41987 = r41981 + r41986;
        double r41988 = r41978 * r41987;
        double r41989 = r41980 + r41988;
        double r41990 = r41978 * r41989;
        double r41991 = r41979 + r41990;
        double r41992 = r41978 * r41991;
        double r41993 = r41975 * r41975;
        double r41994 = -r41993;
        double r41995 = exp(r41994);
        double r41996 = r41992 * r41995;
        double r41997 = r41972 - r41996;
        return r41997;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2020045 
(FPCore (x)
  :name "Jmat.Real.erf"
  :precision binary64
  (- 1 (* (* (/ 1 (+ 1 (* 0.3275911 (fabs x)))) (+ 0.254829592 (* (/ 1 (+ 1 (* 0.3275911 (fabs x)))) (+ -0.284496736 (* (/ 1 (+ 1 (* 0.3275911 (fabs x)))) (+ 1.421413741 (* (/ 1 (+ 1 (* 0.3275911 (fabs x)))) (+ -1.453152027 (* (/ 1 (+ 1 (* 0.3275911 (fabs x)))) 1.061405429))))))))) (exp (- (* (fabs x) (fabs x)))))))

Backtrace

hash-ref: no value found for key key: '(* #<enode 0(351)> #<enode 638(638)>)		L	C
for-loop	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/egraph.rkt	270	6
update-leader!	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/egraph.rkt	265	0
for-loop	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/main.rkt	77	2
prune-phase	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/main.rkt	74	0
for-loop	/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/core/simplify.rkt	80	4
for-loop	/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/core/simplify.rkt	76	2
(unnamed)	/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/core/simplify.rkt	56	0
(unnamed)	/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/core/simplify.rkt	38	0
simplify!	/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/mainloop.rkt	224	0
run-iter!	/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/mainloop.rkt	327	0
for-loop	/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/mainloop.rkt	365	4
run-improve47	/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/mainloop.rkt	346	0
.../more-scheme.rkt:261:28	unknown
run	/opt/racket-7.5/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk16	/opt/racket-7.5/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.5/collects/racket/private/more-scheme.rkt	261	28

Falling back on racket egraph because egg-herbie package not installed (more)

Reproduce

Backtrace