El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\log{\left(\cos{\left(x \right)} \right)} + \cos{\left(x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = \operatorname{acos}{\left(W\left(1\right) \right)}$$
Solución numérica$$x_{1} = 80.7136458790516$$
$$x_{2} = 43.0145340359741$$
$$x_{3} = -95.2155427219768$$
$$x_{4} = 26.1005043430014$$
$$x_{5} = 32.383689650181$$
$$x_{6} = 61.8640899575128$$
$$x_{7} = 63.7996161860789$$
$$x_{8} = 11.5986075000761$$
$$x_{9} = 38.6668749573606$$
$$x_{10} = 0.967763114283042$$
$$x_{11} = -82.6491721076177$$
$$x_{12} = 57.5164308788993$$
$$x_{13} = -30.4481634216149$$
$$x_{14} = -49.2977193431537$$
$$x_{15} = 17.8817928072557$$
$$x_{16} = -93.2800164934108$$
$$x_{17} = -26.1005043430014$$
$$x_{18} = -43.0145340359741$$
$$x_{19} = -70.0828014932585$$
$$x_{20} = 36.7313487287945$$
$$x_{21} = 88.9323574147973$$
$$x_{22} = -63.7996161860789$$
$$x_{23} = 68.1472752646924$$
$$x_{24} = -55.5809046503332$$
$$x_{25} = -61.8640899575128$$
$$x_{26} = -32.383689650181$$
$$x_{27} = -5.31542219289654$$
$$x_{28} = -80.7136458790516$$
$$x_{29} = -0.967763114283042$$
$$x_{30} = -51.2332455717197$$
$$x_{31} = -76.3659868004381$$
$$x_{32} = -11.5986075000761$$
$$x_{33} = 19.8173190358218$$
$$x_{34} = 24.1649781144353$$
$$x_{35} = 86.9968311862312$$
$$x_{36} = -7.25094842146263$$
$$x_{37} = 99.5632018005903$$
$$x_{38} = 44.9500602645401$$
$$x_{39} = 5.31542219289654$$
$$x_{40} = 55.5809046503332$$
$$x_{41} = 49.2977193431537$$
$$x_{42} = -19.8173190358218$$
$$x_{43} = 93.2800164934108$$
$$x_{44} = 70.0828014932585$$
$$x_{45} = -57.5164308788993$$
$$x_{46} = -74.430460571872$$
$$x_{47} = -17.8817928072557$$
$$x_{48} = 76.3659868004381$$
$$x_{49} = 13.5341337286422$$
$$x_{50} = 95.2155427219768$$
$$x_{51} = -24.1649781144353$$
$$x_{52} = -68.1472752646924$$
$$x_{53} = 74.430460571872$$
$$x_{54} = 30.4481634216149$$
$$x_{55} = 82.6491721076177$$
$$x_{56} = -38.6668749573606$$
$$x_{57} = -13.5341337286422$$
$$x_{58} = -99.5632018005903$$