UniformSampleCone, z

Percentage Accurate: 99.9% → 99.9%
Time: 3.7s
Alternatives: 3
Speedup: 1.2×

Specification

?
\[\left(\left(2.328306437 \cdot 10^{-10} \leq ux \land ux \leq 1\right) \land \left(2.328306437 \cdot 10^{-10} \leq uy \land uy \leq 1\right)\right) \land \left(0 \leq maxCos \land maxCos \leq 1\right)\]
\[\begin{array}{l} \\ \left(1 - ux\right) + ux \cdot maxCos \end{array} \]
(FPCore (ux uy maxCos) :precision binary32 (+ (- 1.0 ux) (* ux maxCos)))
float code(float ux, float uy, float maxCos) {
	return (1.0f - ux) + (ux * maxCos);
}
module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(4) function code(ux, uy, maxcos)
use fmin_fmax_functions
    real(4), intent (in) :: ux
    real(4), intent (in) :: uy
    real(4), intent (in) :: maxcos
    code = (1.0e0 - ux) + (ux * maxcos)
end function
function code(ux, uy, maxCos)
	return Float32(Float32(Float32(1.0) - ux) + Float32(ux * maxCos))
end
function tmp = code(ux, uy, maxCos)
	tmp = (single(1.0) - ux) + (ux * maxCos);
end
\begin{array}{l}

\\
\left(1 - ux\right) + ux \cdot maxCos
\end{array}

Sampling outcomes in binary32 precision:

Local Percentage Accuracy vs ?

The average percentage accuracy by input value. Horizontal axis shows value of an input variable; the variable is choosen in the title. Vertical axis is accuracy; higher is better. Red represent the original program, while blue represents Herbie's suggestion. These can be toggled with buttons below the plot. The line is an average while dots represent individual samples.

Accuracy vs Speed?

Herbie found 3 alternatives:

AlternativeAccuracySpeedup
The accuracy (vertical axis) and speed (horizontal axis) of each alternatives. Up and to the right is better. The red square shows the initial program, and each blue circle shows an alternative.The line shows the best available speed-accuracy tradeoffs.

Initial Program: 99.9% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \left(1 - ux\right) + ux \cdot maxCos \end{array} \]
(FPCore (ux uy maxCos) :precision binary32 (+ (- 1.0 ux) (* ux maxCos)))
float code(float ux, float uy, float maxCos) {
	return (1.0f - ux) + (ux * maxCos);
}
module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(4) function code(ux, uy, maxcos)
use fmin_fmax_functions
    real(4), intent (in) :: ux
    real(4), intent (in) :: uy
    real(4), intent (in) :: maxcos
    code = (1.0e0 - ux) + (ux * maxcos)
end function
function code(ux, uy, maxCos)
	return Float32(Float32(Float32(1.0) - ux) + Float32(ux * maxCos))
end
function tmp = code(ux, uy, maxCos)
	tmp = (single(1.0) - ux) + (ux * maxCos);
end
\begin{array}{l}

\\
\left(1 - ux\right) + ux \cdot maxCos
\end{array}

Alternative 1: 99.9% accurate, 1.2× speedup?

\[\begin{array}{l} \\ \mathsf{fma}\left(maxCos - 1, ux, 1\right) \end{array} \]
(FPCore (ux uy maxCos) :precision binary32 (fma (- maxCos 1.0) ux 1.0))
float code(float ux, float uy, float maxCos) {
	return fmaf((maxCos - 1.0f), ux, 1.0f);
}
function code(ux, uy, maxCos)
	return fma(Float32(maxCos - Float32(1.0)), ux, Float32(1.0))
end
\begin{array}{l}

\\
\mathsf{fma}\left(maxCos - 1, ux, 1\right)
\end{array}
Derivation
  1. Initial program 99.9%

    \[\left(1 - ux\right) + ux \cdot maxCos \]
  2. Add Preprocessing
  3. Taylor expanded in maxCos around 0

    \[\leadsto \color{blue}{1 - ux} \]
  4. Step-by-step derivation
    1. lower--.f3297.5

      \[\leadsto \color{blue}{1 - ux} \]
  5. Applied rewrites97.5%

    \[\leadsto \color{blue}{1 - ux} \]
  6. Step-by-step derivation
    1. Applied rewrites96.5%

      \[\leadsto \frac{1 - ux \cdot ux}{\color{blue}{ux + 1}} \]
    2. Taylor expanded in ux around 0

      \[\leadsto \color{blue}{1 + ux \cdot \left(maxCos - 1\right)} \]
    3. Step-by-step derivation
      1. fp-cancel-sign-sub-invN/A

        \[\leadsto \color{blue}{1 - \left(\mathsf{neg}\left(ux\right)\right) \cdot \left(maxCos - 1\right)} \]
      2. mul-1-negN/A

        \[\leadsto 1 - \color{blue}{\left(-1 \cdot ux\right)} \cdot \left(maxCos - 1\right) \]
      3. fp-cancel-sub-sign-invN/A

        \[\leadsto \color{blue}{1 + \left(\mathsf{neg}\left(-1 \cdot ux\right)\right) \cdot \left(maxCos - 1\right)} \]
      4. +-commutativeN/A

        \[\leadsto \color{blue}{\left(\mathsf{neg}\left(-1 \cdot ux\right)\right) \cdot \left(maxCos - 1\right) + 1} \]
      5. mul-1-negN/A

        \[\leadsto \left(\mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(ux\right)\right)}\right)\right) \cdot \left(maxCos - 1\right) + 1 \]
      6. remove-double-negN/A

        \[\leadsto \color{blue}{ux} \cdot \left(maxCos - 1\right) + 1 \]
      7. *-commutativeN/A

        \[\leadsto \color{blue}{\left(maxCos - 1\right) \cdot ux} + 1 \]
      8. lower-fma.f32N/A

        \[\leadsto \color{blue}{\mathsf{fma}\left(maxCos - 1, ux, 1\right)} \]
      9. lower--.f32100.0

        \[\leadsto \mathsf{fma}\left(\color{blue}{maxCos - 1}, ux, 1\right) \]
    4. Applied rewrites100.0%

      \[\leadsto \color{blue}{\mathsf{fma}\left(maxCos - 1, ux, 1\right)} \]
    5. Add Preprocessing

    Alternative 2: 97.9% accurate, 3.0× speedup?

    \[\begin{array}{l} \\ 1 - ux \end{array} \]
    (FPCore (ux uy maxCos) :precision binary32 (- 1.0 ux))
    float code(float ux, float uy, float maxCos) {
    	return 1.0f - ux;
    }
    
    module fmin_fmax_functions
        implicit none
        private
        public fmax
        public fmin
    
        interface fmax
            module procedure fmax88
            module procedure fmax44
            module procedure fmax84
            module procedure fmax48
        end interface
        interface fmin
            module procedure fmin88
            module procedure fmin44
            module procedure fmin84
            module procedure fmin48
        end interface
    contains
        real(8) function fmax88(x, y) result (res)
            real(8), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(x, max(x, y), y /= y), x /= x)
        end function
        real(4) function fmax44(x, y) result (res)
            real(4), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(y, merge(x, max(x, y), y /= y), x /= x)
        end function
        real(8) function fmax84(x, y) result(res)
            real(8), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
        end function
        real(8) function fmax48(x, y) result(res)
            real(4), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
        end function
        real(8) function fmin88(x, y) result (res)
            real(8), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(x, min(x, y), y /= y), x /= x)
        end function
        real(4) function fmin44(x, y) result (res)
            real(4), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(y, merge(x, min(x, y), y /= y), x /= x)
        end function
        real(8) function fmin84(x, y) result(res)
            real(8), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
        end function
        real(8) function fmin48(x, y) result(res)
            real(4), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
        end function
    end module
    
    real(4) function code(ux, uy, maxcos)
    use fmin_fmax_functions
        real(4), intent (in) :: ux
        real(4), intent (in) :: uy
        real(4), intent (in) :: maxcos
        code = 1.0e0 - ux
    end function
    
    function code(ux, uy, maxCos)
    	return Float32(Float32(1.0) - ux)
    end
    
    function tmp = code(ux, uy, maxCos)
    	tmp = single(1.0) - ux;
    end
    
    \begin{array}{l}
    
    \\
    1 - ux
    \end{array}
    
    Derivation
    1. Initial program 99.9%

      \[\left(1 - ux\right) + ux \cdot maxCos \]
    2. Add Preprocessing
    3. Taylor expanded in maxCos around 0

      \[\leadsto \color{blue}{1 - ux} \]
    4. Step-by-step derivation
      1. lower--.f3297.5

        \[\leadsto \color{blue}{1 - ux} \]
    5. Applied rewrites97.5%

      \[\leadsto \color{blue}{1 - ux} \]
    6. Add Preprocessing

    Alternative 3: 71.5% accurate, 12.0× speedup?

    \[\begin{array}{l} \\ 1 \end{array} \]
    (FPCore (ux uy maxCos) :precision binary32 1.0)
    float code(float ux, float uy, float maxCos) {
    	return 1.0f;
    }
    
    module fmin_fmax_functions
        implicit none
        private
        public fmax
        public fmin
    
        interface fmax
            module procedure fmax88
            module procedure fmax44
            module procedure fmax84
            module procedure fmax48
        end interface
        interface fmin
            module procedure fmin88
            module procedure fmin44
            module procedure fmin84
            module procedure fmin48
        end interface
    contains
        real(8) function fmax88(x, y) result (res)
            real(8), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(x, max(x, y), y /= y), x /= x)
        end function
        real(4) function fmax44(x, y) result (res)
            real(4), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(y, merge(x, max(x, y), y /= y), x /= x)
        end function
        real(8) function fmax84(x, y) result(res)
            real(8), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
        end function
        real(8) function fmax48(x, y) result(res)
            real(4), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
        end function
        real(8) function fmin88(x, y) result (res)
            real(8), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(x, min(x, y), y /= y), x /= x)
        end function
        real(4) function fmin44(x, y) result (res)
            real(4), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(y, merge(x, min(x, y), y /= y), x /= x)
        end function
        real(8) function fmin84(x, y) result(res)
            real(8), intent (in) :: x
            real(4), intent (in) :: y
            res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
        end function
        real(8) function fmin48(x, y) result(res)
            real(4), intent (in) :: x
            real(8), intent (in) :: y
            res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
        end function
    end module
    
    real(4) function code(ux, uy, maxcos)
    use fmin_fmax_functions
        real(4), intent (in) :: ux
        real(4), intent (in) :: uy
        real(4), intent (in) :: maxcos
        code = 1.0e0
    end function
    
    function code(ux, uy, maxCos)
    	return Float32(1.0)
    end
    
    function tmp = code(ux, uy, maxCos)
    	tmp = single(1.0);
    end
    
    \begin{array}{l}
    
    \\
    1
    \end{array}
    
    Derivation
    1. Initial program 99.9%

      \[\left(1 - ux\right) + ux \cdot maxCos \]
    2. Add Preprocessing
    3. Taylor expanded in ux around 0

      \[\leadsto \color{blue}{1} \]
    4. Step-by-step derivation
      1. Applied rewrites71.5%

        \[\leadsto \color{blue}{1} \]
      2. Add Preprocessing

      Reproduce

      ?
      herbie shell --seed 2024351 
      (FPCore (ux uy maxCos)
        :name "UniformSampleCone, z"
        :precision binary32
        :pre (and (and (and (<= 2.328306437e-10 ux) (<= ux 1.0)) (and (<= 2.328306437e-10 uy) (<= uy 1.0))) (and (<= 0.0 maxCos) (<= maxCos 1.0)))
        (+ (- 1.0 ux) (* ux maxCos)))