El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\tan{\left(\tan{\left(\tan{\left(\tan{\left(x \right)} \right)} \right)} \right)} - 1 = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = \operatorname{atan}{\left(\operatorname{atan}{\left(\operatorname{atan}{\left(\frac{\pi}{4} \right)} \right)} \right)}$$
Solución numérica$$x_{1} = -63.7025185492294$$
$$x_{2} = 86.2492645429153$$
$$x_{3} = 75.9293151963108$$
$$x_{4} = -37.1680203329218$$
$$x_{5} = -49.7343909472809$$
$$x_{6} = -68.5839468688197$$
$$x_{7} = -25.8449266329477$$
$$x_{8} = -86.0206312958681$$
$$x_{9} = -90.5750954439481$$
$$x_{10} = -92.0549129210679$$
$$x_{11} = 101.451216293452$$
$$x_{12} = 96.5187067838501$$
$$x_{13} = 90.2355214766705$$
$$x_{14} = 64.2581159677868$$
$$x_{15} = 42.8349654400481$$
$$x_{16} = 19.3806474316945$$
$$x_{17} = -27.7432423721524$$
$$x_{18} = -43.4512056401013$$
$$x_{19} = -79.7374459886885$$
$$x_{20} = -3.92414864765278$$
$$x_{21} = -71.7255395224095$$
$$x_{22} = -12.0352791042034$$
$$x_{23} = -35.7551488384314$$
$$x_{24} = 60.2213519283618$$
$$x_{25} = -17.7516411791057$$
$$x_{26} = -43.1486285828937$$
$$x_{27} = -99.9998734047176$$
$$x_{28} = -96.0805813981521$$
$$x_{29} = -78.0087248295891$$
$$x_{30} = 98.3096236398618$$
$$x_{31} = 48.4326806669784$$
$$x_{32} = 82.2125005034904$$
$$x_{33} = 94.7788711178496$$
$$x_{34} = 24.2620757512848$$
$$x_{35} = 46.2532243264134$$
$$x_{36} = 14.2498431959961$$
$$x_{37} = 75.9293151963108$$
$$x_{38} = -5.75209379702383$$
$$x_{39} = -55.8032941633785$$
$$x_{40} = 16.2390547781047$$
$$x_{41} = 91.9398555214674$$
$$x_{42} = -13.7640002633028$$
$$x_{43} = -0.712185404229327$$
$$x_{44} = 42.7846675013135$$
$$x_{45} = -2.04367791115677$$
$$x_{46} = 0.531091510155762$$
$$x_{47} = 53.9381666211822$$
$$x_{48} = -57.7462974135599$$
$$x_{49} = -46.5927982936911$$
$$x_{50} = 38.2302033532333$$
$$x_{51} = -93.716688097538$$
$$x_{52} = -709.468848201137$$
$$x_{53} = 9.95586947092514$$
$$x_{54} = 4.06184403216802$$
$$x_{55} = 28.8054253924639$$
$$x_{56} = -51.8727443194123$$
$$x_{57} = 32.2495951032613$$
$$x_{58} = 57.9986642593673$$
$$x_{59} = 7.93726803943923$$
$$x_{60} = -34.026427679332$$
$$x_{61} = -59.1591689080503$$
$$x_{62} = 70.2129531214085$$
$$x_{63} = -14.3389424380385$$
$$x_{64} = 41.7609558752455$$
$$x_{65} = -61.7339383293628$$
$$x_{66} = -23.7064783327274$$
$$x_{67} = -7.92124445012173$$