HairBSDF, Mp, upper

Average Error: 0.5 → 0.4

Time: 20.6s

Precision: binary32

Cost: 7168

\[\left(\left(\left(\left(\left(-1 \leq cosTheta_i \land cosTheta_i \leq 1\right) \land \left(-1 \leq cosTheta_O \land cosTheta_O \leq 1\right)\right) \land \left(-1 \leq sinTheta_i \land sinTheta_i \leq 1\right)\right) \land \left(-1 \leq sinTheta_O \land sinTheta_O \leq 1\right)\right) \land 0.1 < v\right) \land v \leq 1.5707964\]

\[ \begin{array}{c}[cosTheta_i, cosTheta_O] = \mathsf{sort}([cosTheta_i, cosTheta_O])\\ \end{array} \]

Math

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

↓

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

FPCore

(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v)
 :precision binary32
 (/
  (* (exp (- (/ (* sinTheta_i sinTheta_O) v))) (/ (* cosTheta_i cosTheta_O) v))
  (* (* (sinh (/ 1.0 v)) 2.0) v)))

↓

(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v)
 :precision binary32
 (/
  (*
   (exp (/ (* sinTheta_i (- sinTheta_O)) v))
   (* cosTheta_i (* cosTheta_O (/ 1.0 v))))
  (/ (* (sinh (/ 1.0 v)) 2.0) (/ 1.0 v))))

C

float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
	return (expf(-((sinTheta_i * sinTheta_O) / v)) * ((cosTheta_i * cosTheta_O) / v)) / ((sinhf((1.0f / v)) * 2.0f) * v);
}

↓

float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
	return (expf(((sinTheta_i * -sinTheta_O) / v)) * (cosTheta_i * (cosTheta_O * (1.0f / v)))) / ((sinhf((1.0f / v)) * 2.0f) / (1.0f / v));
}

Fortran

real(4) function code(costheta_i, costheta_o, sintheta_i, sintheta_o, v)
    real(4), intent (in) :: costheta_i
    real(4), intent (in) :: costheta_o
    real(4), intent (in) :: sintheta_i
    real(4), intent (in) :: sintheta_o
    real(4), intent (in) :: v
    code = (exp(-((sintheta_i * sintheta_o) / v)) * ((costheta_i * costheta_o) / v)) / ((sinh((1.0e0 / v)) * 2.0e0) * v)
end function

↓

real(4) function code(costheta_i, costheta_o, sintheta_i, sintheta_o, v)
    real(4), intent (in) :: costheta_i
    real(4), intent (in) :: costheta_o
    real(4), intent (in) :: sintheta_i
    real(4), intent (in) :: sintheta_o
    real(4), intent (in) :: v
    code = (exp(((sintheta_i * -sintheta_o) / v)) * (costheta_i * (costheta_o * (1.0e0 / v)))) / ((sinh((1.0e0 / v)) * 2.0e0) / (1.0e0 / v))
end function

Julia

function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v)
	return Float32(Float32(exp(Float32(-Float32(Float32(sinTheta_i * sinTheta_O) / v))) * Float32(Float32(cosTheta_i * cosTheta_O) / v)) / Float32(Float32(sinh(Float32(Float32(1.0) / v)) * Float32(2.0)) * v))
end

↓

function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v)
	return Float32(Float32(exp(Float32(Float32(sinTheta_i * Float32(-sinTheta_O)) / v)) * Float32(cosTheta_i * Float32(cosTheta_O * Float32(Float32(1.0) / v)))) / Float32(Float32(sinh(Float32(Float32(1.0) / v)) * Float32(2.0)) / Float32(Float32(1.0) / v)))
end

MATLAB

function tmp = code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v)
	tmp = (exp(-((sinTheta_i * sinTheta_O) / v)) * ((cosTheta_i * cosTheta_O) / v)) / ((sinh((single(1.0) / v)) * single(2.0)) * v);
end

↓

function tmp = code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v)
	tmp = (exp(((sinTheta_i * -sinTheta_O) / v)) * (cosTheta_i * (cosTheta_O * (single(1.0) / v)))) / ((sinh((single(1.0) / v)) * single(2.0)) / (single(1.0) / v));
end

Derivation

1. Initial program 0.5

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

2. Applied egg-rr 0.4

   \[\leadsto \frac{e^{-\frac{sinTheta_i \cdot sinTheta_O}{v}} \cdot \color{blue}{\left(cosTheta_i \cdot \left(cosTheta_O \cdot \frac{1}{v}\right)\right)}}{\left(\sinh \left(\frac{1}{v}\right) \cdot 2\right) \cdot v} \]

3. Applied egg-rr 0.4

   \[\leadsto \frac{e^{-\frac{sinTheta_i \cdot sinTheta_O}{v}} \cdot \left(cosTheta_i \cdot \left(cosTheta_O \cdot \frac{1}{v}\right)\right)}{\color{blue}{\frac{\sinh \left(\frac{1}{v}\right) \cdot 2}{\frac{1}{v}}}} \]

4. Final simplification 0.4

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

Alternatives

Alternative 1
Error	0.4
Cost	7104

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

Alternative 2
Error	0.4
Cost	7104

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

Alternative 3
Error	0.4
Cost	7104

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

Alternative 4
Error	0.5
Cost	7040

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

Alternative 5
Error	0.4
Cost	7008

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

Alternative 6
Error	0.5
Cost	6944

\[\left(cosTheta_i \cdot \frac{cosTheta_O}{v}\right) \cdot \frac{\frac{1}{v}}{e^{\frac{1}{v}} - e^{\frac{-1}{v}}} \]

Alternative 7
Error	0.5
Cost	6880

\[\frac{cosTheta_i}{v \cdot v} \cdot \frac{cosTheta_O}{e^{\frac{1}{v}} - e^{\frac{-1}{v}}} \]

Alternative 8
Error	8.6
Cost	4164

\[\begin{array}{l} \mathbf{if}\;v \leq 0.5199999809265137:\\ \;\;\;\;\frac{cosTheta_i \cdot cosTheta_O}{v \cdot \left(v \cdot \mathsf{expm1}\left(\frac{1}{v}\right)\right)}\\ \mathbf{else}:\\ \;\;\;\;\frac{cosTheta_i}{v \cdot v} \cdot \left(\frac{cosTheta_O \cdot 0.013888888888888888 - cosTheta_O \cdot 0.004166666666666667}{{v}^{3}} + \left(\frac{cosTheta_O}{v} \cdot -0.08333333333333333 + 0.5 \cdot \left(v \cdot cosTheta_O\right)\right)\right)\\ \end{array} \]

Alternative 9
Error	8.6
Cost	3908

\[\begin{array}{l} \mathbf{if}\;v \leq 0.5199999809265137:\\ \;\;\;\;\frac{cosTheta_i \cdot cosTheta_O}{v \cdot \left(v \cdot \mathsf{expm1}\left(\frac{1}{v}\right)\right)}\\ \mathbf{else}:\\ \;\;\;\;\left(\frac{0.009722222222222222}{{v}^{3}} + \left(v \cdot 0.5 + \frac{-0.08333333333333333}{v}\right)\right) \cdot \frac{\frac{cosTheta_i \cdot cosTheta_O}{v}}{v}\\ \end{array} \]

Alternative 10
Error	8.9
Cost	3812

\[\begin{array}{l} \mathbf{if}\;v \leq 0.44999998807907104:\\ \;\;\;\;\frac{cosTheta_i \cdot cosTheta_O}{v \cdot \left(v \cdot \mathsf{expm1}\left(\frac{1}{v}\right)\right)}\\ \mathbf{else}:\\ \;\;\;\;\frac{cosTheta_i \cdot cosTheta_O}{\left(v \cdot 2 + \frac{0.3333333333333333}{v}\right) \cdot e^{sinTheta_i \cdot \frac{sinTheta_O}{v}}}\\ \end{array} \]

Alternative 11
Error	10.0
Cost	3552

\[cosTheta_O \cdot \frac{cosTheta_i}{v \cdot \left(v \cdot \mathsf{expm1}\left(\frac{1}{v}\right)\right)} \]

Alternative 12
Error	10.0
Cost	3552

\[\frac{cosTheta_O \cdot \frac{cosTheta_i}{v}}{v \cdot \mathsf{expm1}\left(\frac{1}{v}\right)} \]

Alternative 13
Error	13.2
Cost	480

\[\left(cosTheta_i \cdot \frac{cosTheta_O}{v}\right) \cdot \left(0.5 + \frac{sinTheta_i \cdot sinTheta_O}{v} \cdot -0.5\right) \]

Alternative 14
Error	13.2
Cost	224

\[0.5 \cdot \left(cosTheta_O \cdot \frac{cosTheta_i}{v}\right) \]

Alternative 15
Error	13.2
Cost	224

\[\left(cosTheta_i \cdot \frac{cosTheta_O}{v}\right) \cdot 0.5 \]

Alternative 16
Error	14.0
Cost	160

\[cosTheta_O \cdot \frac{cosTheta_i}{v} \]

Alternative 17
Error	14.0
Cost	160

\[cosTheta_i \cdot \frac{cosTheta_O}{v} \]

Alternative 18
Error	14.0
Cost	160

\[\frac{cosTheta_O}{\frac{v}{cosTheta_i}} \]

Alternative 19
Error	14.0
Cost	160

\[\frac{cosTheta_i \cdot cosTheta_O}{v} \]

Reproduce

herbie shell --seed 2023018 
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v)
  :name "HairBSDF, Mp, upper"
  :precision binary32
  :pre (and (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))) (< 0.1 v)) (<= v 1.5707964))
  (/ (* (exp (- (/ (* sinTheta_i sinTheta_O) v))) (/ (* cosTheta_i cosTheta_O) v)) (* (* (sinh (/ 1.0 v)) 2.0) v)))