El gráfico de la función cruce el eje Y con f = 0
o sea hay que resolver la ecuación:
$$\log{\left(\frac{1}{\cos{\left(y \right)}} \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje Y:
Solución analítica$$y_{1} = 0$$
$$y_{2} = 2 \pi$$
Solución numérica$$y_{1} = 6.28318528416623$$
$$y_{2} = -25.1327401930409$$
$$y_{3} = -18.8495553258088$$
$$y_{4} = -87.9645943584596$$
$$y_{5} = 56.5486679766099$$
$$y_{6} = 18.8495570029843$$
$$y_{7} = -87.9645943355219$$
$$y_{8} = -31.4159267264704$$
$$y_{9} = -50.2654822771894$$
$$y_{10} = -81.6814089617871$$
$$y_{11} = 31.4159255304025$$
$$y_{12} = 69.1150390127643$$
$$y_{13} = -94.2477794374461$$
$$y_{14} = 87.9645943360512$$
$$y_{15} = 25.1327418431203$$
$$y_{16} = -94.2477799001796$$
$$y_{17} = -12.5663716213936$$
$$y_{18} = 69.1150381807919$$
$$y_{19} = 62.8318538684035$$
$$y_{20} = -18.8495562408585$$
$$y_{21} = -56.5486688343165$$
$$y_{22} = -75.3982234018825$$
$$y_{23} = -6.28318511692891$$
$$y_{24} = 50.2654824640562$$
$$y_{25} = 43.9822971695019$$
$$y_{26} = -69.1150387500801$$
$$y_{27} = -69.1150374752626$$
$$y_{28} = -12.5663716386669$$
$$y_{29} = -18.8495557286473$$
$$y_{30} = 69.1150378238503$$
$$y_{31} = -81.6814090384469$$
$$y_{32} = 87.9645942296464$$
$$y_{33} = -56.5486674143785$$
$$y_{34} = 18.8495567580196$$
$$y_{35} = 62.831852735923$$
$$y_{36} = 25.1327406563971$$
$$y_{37} = -37.6991118773736$$
$$y_{38} = 94.2477796068599$$
$$y_{39} = 12.5663708485373$$
$$y_{40} = 94.2477796093522$$
$$y_{41} = -62.8318528736237$$
$$y_{42} = -6.28318566745615$$
$$y_{43} = -62.8318524940769$$
$$y_{44} = -31.4159262776781$$
$$y_{45} = 43.982297089421$$
$$y_{46} = -62.8318536803612$$
$$y_{47} = -50.2654827822791$$
$$y_{48} = -43.9822971744998$$
$$y_{49} = 69.1150390932802$$
$$y_{50} = 81.6814085526449$$
$$y_{51} = -100.53096457631$$
$$y_{52} = 37.6991120433529$$
$$y_{53} = 50.2654824463311$$
$$y_{54} = 0$$
$$y_{55} = 75.3982226911418$$
$$y_{56} = 75.3982227418079$$
$$y_{57} = -37.6991118203008$$
$$y_{58} = -25.1327403562086$$
$$y_{59} = 62.8318542034359$$
$$y_{60} = -12.5663702522378$$
$$y_{61} = 81.681409203672$$
$$y_{62} = 12.5663704334084$$
$$y_{63} = 31.4159255531763$$
$$y_{64} = 56.5486675932357$$
$$y_{65} = 25.1327409700176$$
$$y_{66} = -25.1327415878584$$
$$y_{67} = 31.4159269101267$$
$$y_{68} = 100.530965106382$$
$$y_{69} = -75.3982238864105$$
$$y_{70} = -56.5486687640637$$
$$y_{71} = 75.39822407273$$
$$y_{72} = -18.8495565116576$$
$$y_{73} = 6.28318532165763$$
$$y_{74} = -69.1150373853363$$
$$y_{75} = 37.6991114441887$$
$$y_{76} = 18.8495555741382$$
$$y_{77} = 100.530964753022$$
$$y_{78} = 25.1327418930934$$
$$y_{79} = -100.530965897751$$
$$y_{80} = -43.9822971932261$$
$$y_{81} = -62.8318534517187$$