\[\cos \left(x + \varepsilon\right) - \cos x\]
Test:
NMSE problem 3.3.5
Bits:
128 bits
Bits error versus x
Bits error versus eps
Time: 11.3 s
Input Error: 18.6
Output Error: 0.6
Log:
Profile: 🕒
\(\begin{cases} {\left(\cos x \cdot \cos \varepsilon\right)}^{1} - \left(\sin x \cdot \sin \varepsilon + \cos x\right) & \text{when } \varepsilon \le -0.0011342058f0 \\ \left(\varepsilon \cdot \varepsilon\right) \cdot \frac{-1}{2} - \sin \varepsilon \cdot \sin x & \text{when } \varepsilon \le 0.25760502f0 \\ {\left(\cos x \cdot \cos \varepsilon\right)}^{1} - \left(\sin x \cdot \sin \varepsilon + \cos x\right) & \text{otherwise} \end{cases}\)

    if eps < -0.0011342058f0 or 0.25760502f0 < eps

    1. Started with
      \[\cos \left(x + \varepsilon\right) - \cos x\]
      14.5
    2. Using strategy rm
      14.5
    3. Applied cos-sum to get
      \[\color{red}{\cos \left(x + \varepsilon\right)} - \cos x \leadsto \color{blue}{\left(\cos x \cdot \cos \varepsilon - \sin x \cdot \sin \varepsilon\right)} - \cos x\]
      0.9
    4. Applied associate--l- to get
      \[\color{red}{\left(\cos x \cdot \cos \varepsilon - \sin x \cdot \sin \varepsilon\right) - \cos x} \leadsto \color{blue}{\cos x \cdot \cos \varepsilon - \left(\sin x \cdot \sin \varepsilon + \cos x\right)}\]
      0.9
    5. Using strategy rm
      0.9
    6. Applied pow1 to get
      \[\cos x \cdot \color{red}{\cos \varepsilon} - \left(\sin x \cdot \sin \varepsilon + \cos x\right) \leadsto \cos x \cdot \color{blue}{{\left(\cos \varepsilon\right)}^{1}} - \left(\sin x \cdot \sin \varepsilon + \cos x\right)\]
      0.9
    7. Applied pow1 to get
      \[\color{red}{\cos x} \cdot {\left(\cos \varepsilon\right)}^{1} - \left(\sin x \cdot \sin \varepsilon + \cos x\right) \leadsto \color{blue}{{\left(\cos x\right)}^{1}} \cdot {\left(\cos \varepsilon\right)}^{1} - \left(\sin x \cdot \sin \varepsilon + \cos x\right)\]
      0.9
    8. Applied pow-prod-down to get
      \[\color{red}{{\left(\cos x\right)}^{1} \cdot {\left(\cos \varepsilon\right)}^{1}} - \left(\sin x \cdot \sin \varepsilon + \cos x\right) \leadsto \color{blue}{{\left(\cos x \cdot \cos \varepsilon\right)}^{1}} - \left(\sin x \cdot \sin \varepsilon + \cos x\right)\]
      1.0

    if -0.0011342058f0 < eps < 0.25760502f0

    1. Started with
      \[\cos \left(x + \varepsilon\right) - \cos x\]
      23.3
    2. Using strategy rm
      23.3
    3. Applied cos-sum to get
      \[\color{red}{\cos \left(x + \varepsilon\right)} - \cos x \leadsto \color{blue}{\left(\cos x \cdot \cos \varepsilon - \sin x \cdot \sin \varepsilon\right)} - \cos x\]
      18.7
    4. Applied associate--l- to get
      \[\color{red}{\left(\cos x \cdot \cos \varepsilon - \sin x \cdot \sin \varepsilon\right) - \cos x} \leadsto \color{blue}{\cos x \cdot \cos \varepsilon - \left(\sin x \cdot \sin \varepsilon + \cos x\right)}\]
      18.7
    5. Using strategy rm
      18.7
    6. Applied add-log-exp to get
      \[\cos x \cdot \cos \varepsilon - \left(\sin x \cdot \sin \varepsilon + \color{red}{\cos x}\right) \leadsto \cos x \cdot \cos \varepsilon - \left(\sin x \cdot \sin \varepsilon + \color{blue}{\log \left(e^{\cos x}\right)}\right)\]
      20.6
    7. Applied add-log-exp to get
      \[\cos x \cdot \cos \varepsilon - \left(\color{red}{\sin x \cdot \sin \varepsilon} + \log \left(e^{\cos x}\right)\right) \leadsto \cos x \cdot \cos \varepsilon - \left(\color{blue}{\log \left(e^{\sin x \cdot \sin \varepsilon}\right)} + \log \left(e^{\cos x}\right)\right)\]
      22.7
    8. Applied sum-log to get
      \[\cos x \cdot \cos \varepsilon - \color{red}{\left(\log \left(e^{\sin x \cdot \sin \varepsilon}\right) + \log \left(e^{\cos x}\right)\right)} \leadsto \cos x \cdot \cos \varepsilon - \color{blue}{\log \left(e^{\sin x \cdot \sin \varepsilon} \cdot e^{\cos x}\right)}\]
      22.7
    9. Applied add-log-exp to get
      \[\color{red}{\cos x \cdot \cos \varepsilon} - \log \left(e^{\sin x \cdot \sin \varepsilon} \cdot e^{\cos x}\right) \leadsto \color{blue}{\log \left(e^{\cos x \cdot \cos \varepsilon}\right)} - \log \left(e^{\sin x \cdot \sin \varepsilon} \cdot e^{\cos x}\right)\]
      22.5
    10. Applied diff-log to get
      \[\color{red}{\log \left(e^{\cos x \cdot \cos \varepsilon}\right) - \log \left(e^{\sin x \cdot \sin \varepsilon} \cdot e^{\cos x}\right)} \leadsto \color{blue}{\log \left(\frac{e^{\cos x \cdot \cos \varepsilon}}{e^{\sin x \cdot \sin \varepsilon} \cdot e^{\cos x}}\right)}\]
      22.5
    11. Applied simplify to get
      \[\log \color{red}{\left(\frac{e^{\cos x \cdot \cos \varepsilon}}{e^{\sin x \cdot \sin \varepsilon} \cdot e^{\cos x}}\right)} \leadsto \log \color{blue}{\left(e^{\left(\cos \varepsilon \cdot \cos x - \cos x\right) - \sin x \cdot \sin \varepsilon}\right)}\]
      22.4
    12. Applied taylor to get
      \[\log \left(e^{\left(\cos \varepsilon \cdot \cos x - \cos x\right) - \sin x \cdot \sin \varepsilon}\right) \leadsto \log \left(e^{\frac{-1}{2} \cdot {\varepsilon}^2 - \sin x \cdot \sin \varepsilon}\right)\]
      22.2
    13. Taylor expanded around 0 to get
      \[\log \left(e^{\color{red}{\frac{-1}{2} \cdot {\varepsilon}^2} - \sin x \cdot \sin \varepsilon}\right) \leadsto \log \left(e^{\color{blue}{\frac{-1}{2} \cdot {\varepsilon}^2} - \sin x \cdot \sin \varepsilon}\right)\]
      22.2
    14. Applied simplify to get
      \[\log \left(e^{\frac{-1}{2} \cdot {\varepsilon}^2 - \sin x \cdot \sin \varepsilon}\right) \leadsto \left(\varepsilon \cdot \varepsilon\right) \cdot \frac{-1}{2} - \sin \varepsilon \cdot \sin x\]
      0.2

    15. Applied final simplification

  1. Removed slow pow expressions

Original test:


(lambda ((x default) (eps default))
  #:name "NMSE problem 3.3.5"
  (- (cos (+ x eps)) (cos x)))