El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\log{\left(- \sqrt{2} \cos{\left(x \right)} \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = \frac{3 \pi}{4}$$
$$x_{2} = \frac{5 \pi}{4}$$
Solución numérica$$x_{1} = -8.63937979737193$$
$$x_{2} = 10.2101761241668$$
$$x_{3} = 66.7588438887831$$
$$x_{4} = 8.63937979737193$$
$$x_{5} = -90.3207887907066$$
$$x_{6} = 96.6039740978861$$
$$x_{7} = -91.8915851175014$$
$$x_{8} = 3.92699081698724$$
$$x_{9} = 65.1880475619882$$
$$x_{10} = -29.0597320457056$$
$$x_{11} = -3.92699081698724$$
$$x_{12} = -35.3429173528852$$
$$x_{13} = -54.1924732744239$$
$$x_{14} = -52.621676947629$$
$$x_{15} = 47.9092879672443$$
$$x_{16} = 21.2057504117311$$
$$x_{17} = 27.4889357189107$$
$$x_{18} = -10.2101761241668$$
$$x_{19} = -16.4933614313464$$
$$x_{20} = 98.174770424681$$
$$x_{21} = 14.9225651045515$$
$$x_{22} = 58.9048622548086$$
$$x_{23} = 41.6261026600648$$
$$x_{24} = 77.7544181763474$$
$$x_{25} = -85.6083998103219$$
$$x_{26} = -33.7721210260903$$
$$x_{27} = -14.9225651045515$$
$$x_{28} = 79.3252145031423$$
$$x_{29} = -46.3384916404494$$
$$x_{30} = 2.35619449019234$$
$$x_{31} = 22.776546738526$$
$$x_{32} = -21.2057504117311$$
$$x_{33} = 60.4756585816035$$
$$x_{34} = -60.4756585816035$$
$$x_{35} = -77.7544181763474$$
$$x_{36} = 90.3207887907066$$
$$x_{37} = -73.0420291959627$$
$$x_{38} = 40.0553063332699$$
$$x_{39} = 29.0597320457056$$
$$x_{40} = -41.6261026600648$$
$$x_{41} = -96.6039740978861$$
$$x_{42} = -98.174770424681$$
$$x_{43} = 84.037603483527$$
$$x_{44} = 54.1924732744239$$
$$x_{45} = -22.776546738526$$
$$x_{46} = -71.4712328691678$$
$$x_{47} = 33.7721210260903$$
$$x_{48} = 46.3384916404494$$
$$x_{49} = 35.3429173528852$$
$$x_{50} = -27.4889357189107$$
$$x_{51} = 85.6083998103219$$
$$x_{52} = 52.621676947629$$
$$x_{53} = 73.0420291959627$$
$$x_{54} = -2.35619449019234$$
$$x_{55} = -47.9092879672443$$
$$x_{56} = -65.1880475619882$$
$$x_{57} = -84.037603483527$$
$$x_{58} = -79.3252145031423$$
$$x_{59} = -66.7588438887831$$
$$x_{60} = -40.0553063332699$$
$$x_{61} = 16.4933614313464$$
$$x_{62} = -58.9048622548086$$
$$x_{63} = 91.8915851175014$$