Average Error: 0.1 → 0.1
Time: 11.5s
Precision: binary32
\[\left(\left(\left(\left(-1 \leq cosTheta_i \land cosTheta_i \leq 1\right) \land \left(-1 \leq cosTheta_O \land cosTheta_O \leq 1\right)\right) \land \left(-1 \leq sinTheta_i \land sinTheta_i \leq 1\right)\right) \land \left(-1 \leq sinTheta_O \land sinTheta_O \leq 1\right)\right) \land \left(-1.5707964 \leq v \land v \leq 0.1\right)\]
\[e^{\left(\left(\left(\frac{cosTheta_i \cdot cosTheta_O}{v} - \frac{sinTheta_i \cdot sinTheta_O}{v}\right) - \frac{1}{v}\right) + 0.6931\right) + \log \left(\frac{1}{2 \cdot v}\right)} \]
↓
\[\begin{array}{l} t_0 := \sqrt[3]{\frac{0.5}{v}}\\ \left({\left(\sqrt[3]{t_0}\right)}^{4} \cdot \sqrt[3]{{t_0}^{2}}\right) \cdot \left(t_0 \cdot e^{\mathsf{fma}\left(cosTheta_O, \frac{cosTheta_i}{v}, 0.6931\right) - \mathsf{fma}\left(sinTheta_i, \frac{sinTheta_O}{v}, \frac{1}{v}\right)}\right) \end{array} \]
e^{\left(\left(\left(\frac{cosTheta_i \cdot cosTheta_O}{v} - \frac{sinTheta_i \cdot sinTheta_O}{v}\right) - \frac{1}{v}\right) + 0.6931\right) + \log \left(\frac{1}{2 \cdot v}\right)}
↓
\begin{array}{l}
t_0 := \sqrt[3]{\frac{0.5}{v}}\\
\left({\left(\sqrt[3]{t_0}\right)}^{4} \cdot \sqrt[3]{{t_0}^{2}}\right) \cdot \left(t_0 \cdot e^{\mathsf{fma}\left(cosTheta_O, \frac{cosTheta_i}{v}, 0.6931\right) - \mathsf{fma}\left(sinTheta_i, \frac{sinTheta_O}{v}, \frac{1}{v}\right)}\right)
\end{array}

(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v)
 :precision binary32
 (exp
  (+
   (+
    (-
     (- (/ (* cosTheta_i cosTheta_O) v) (/ (* sinTheta_i sinTheta_O) v))
     (/ 1.0 v))
    0.6931)
   (log (/ 1.0 (* 2.0 v))))))
↓
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v)
 :precision binary32
 (let* ((t_0 (cbrt (/ 0.5 v))))
   (*
    (* (pow (cbrt t_0) 4.0) (cbrt (pow t_0 2.0)))
    (*
     t_0
     (exp
      (-
       (fma cosTheta_O (/ cosTheta_i v) 0.6931)
       (fma sinTheta_i (/ sinTheta_O v) (/ 1.0 v))))))))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
	return expf((((((cosTheta_i * cosTheta_O) / v) - ((sinTheta_i * sinTheta_O) / v)) - (1.0f / v)) + 0.6931f) + logf(1.0f / (2.0f * v)));
}
↓
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
	float t_0 = cbrtf(0.5f / v);
	return (powf(cbrtf(t_0), 4.0f) * cbrtf(powf(t_0, 2.0f))) * (t_0 * expf(fmaf(cosTheta_O, (cosTheta_i / v), 0.6931f) - fmaf(sinTheta_i, (sinTheta_O / v), (1.0f / v))));
}

Error

Bits error versus cosTheta_i

Bits error versus cosTheta_O

Bits error versus sinTheta_i

Bits error versus sinTheta_O

Bits error versus v

Derivation

  1. Initial program 0.1

    \[e^{\left(\left(\left(\frac{cosTheta_i \cdot cosTheta_O}{v} - \frac{sinTheta_i \cdot sinTheta_O}{v}\right) - \frac{1}{v}\right) + 0.6931\right) + \log \left(\frac{1}{2 \cdot v}\right)} \]

  2. Simplified0.1

    \[\leadsto \color{blue}{\frac{0.5}{v} \cdot e^{\mathsf{fma}\left(cosTheta_O, \frac{cosTheta_i}{v}, 0.6931\right) - \mathsf{fma}\left(sinTheta_i, \frac{sinTheta_O}{v}, \frac{1}{v}\right)}} \]

  3. Applied add-cube-cbrt_binary320.1

    \[\leadsto \color{blue}{\left(\left(\sqrt[3]{\frac{0.5}{v}} \cdot \sqrt[3]{\frac{0.5}{v}}\right) \cdot \sqrt[3]{\frac{0.5}{v}}\right)} \cdot e^{\mathsf{fma}\left(cosTheta_O, \frac{cosTheta_i}{v}, 0.6931\right) - \mathsf{fma}\left(sinTheta_i, \frac{sinTheta_O}{v}, \frac{1}{v}\right)} \]

  4. Applied associate-*l*_binary320.1

    \[\leadsto \color{blue}{\left(\sqrt[3]{\frac{0.5}{v}} \cdot \sqrt[3]{\frac{0.5}{v}}\right) \cdot \left(\sqrt[3]{\frac{0.5}{v}} \cdot e^{\mathsf{fma}\left(cosTheta_O, \frac{cosTheta_i}{v}, 0.6931\right) - \mathsf{fma}\left(sinTheta_i, \frac{sinTheta_O}{v}, \frac{1}{v}\right)}\right)} \]

  5. Applied add-cube-cbrt_binary320.1

    \[\leadsto \color{blue}{\left(\left(\sqrt[3]{\sqrt[3]{\frac{0.5}{v}} \cdot \sqrt[3]{\frac{0.5}{v}}} \cdot \sqrt[3]{\sqrt[3]{\frac{0.5}{v}} \cdot \sqrt[3]{\frac{0.5}{v}}}\right) \cdot \sqrt[3]{\sqrt[3]{\frac{0.5}{v}} \cdot \sqrt[3]{\frac{0.5}{v}}}\right)} \cdot \left(\sqrt[3]{\frac{0.5}{v}} \cdot e^{\mathsf{fma}\left(cosTheta_O, \frac{cosTheta_i}{v}, 0.6931\right) - \mathsf{fma}\left(sinTheta_i, \frac{sinTheta_O}{v}, \frac{1}{v}\right)}\right) \]

  6. Simplified0.1

    \[\leadsto \left(\color{blue}{{\left(\sqrt[3]{\sqrt[3]{\frac{0.5}{v}}}\right)}^{4}} \cdot \sqrt[3]{\sqrt[3]{\frac{0.5}{v}} \cdot \sqrt[3]{\frac{0.5}{v}}}\right) \cdot \left(\sqrt[3]{\frac{0.5}{v}} \cdot e^{\mathsf{fma}\left(cosTheta_O, \frac{cosTheta_i}{v}, 0.6931\right) - \mathsf{fma}\left(sinTheta_i, \frac{sinTheta_O}{v}, \frac{1}{v}\right)}\right) \]

  7. Simplified0.1

    \[\leadsto \left({\left(\sqrt[3]{\sqrt[3]{\frac{0.5}{v}}}\right)}^{4} \cdot \color{blue}{\sqrt[3]{{\left(\sqrt[3]{\frac{0.5}{v}}\right)}^{2}}}\right) \cdot \left(\sqrt[3]{\frac{0.5}{v}} \cdot e^{\mathsf{fma}\left(cosTheta_O, \frac{cosTheta_i}{v}, 0.6931\right) - \mathsf{fma}\left(sinTheta_i, \frac{sinTheta_O}{v}, \frac{1}{v}\right)}\right) \]

  8. Final simplification0.1

    \[\leadsto \left({\left(\sqrt[3]{\sqrt[3]{\frac{0.5}{v}}}\right)}^{4} \cdot \sqrt[3]{{\left(\sqrt[3]{\frac{0.5}{v}}\right)}^{2}}\right) \cdot \left(\sqrt[3]{\frac{0.5}{v}} \cdot e^{\mathsf{fma}\left(cosTheta_O, \frac{cosTheta_i}{v}, 0.6931\right) - \mathsf{fma}\left(sinTheta_i, \frac{sinTheta_O}{v}, \frac{1}{v}\right)}\right) \]

Reproduce

herbie shell --seed 2022061 
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v)
  :name "HairBSDF, Mp, lower"
  :precision binary32
  :pre (and (and (and (and (and (<= -1.0 cosTheta_i) (<= cosTheta_i 1.0)) (and (<= -1.0 cosTheta_O) (<= cosTheta_O 1.0))) (and (<= -1.0 sinTheta_i) (<= sinTheta_i 1.0))) (and (<= -1.0 sinTheta_O) (<= sinTheta_O 1.0))) (and (<= -1.5707964 v) (<= v 0.1)))
  (exp (+ (+ (- (- (/ (* cosTheta_i cosTheta_O) v) (/ (* sinTheta_i sinTheta_O) v)) (/ 1.0 v)) 0.6931) (log (/ 1.0 (* 2.0 v))))))