Let's find the inflection points, we'll need to solve the equation for this
$$\frac{d^{2}}{d t^{2}} f{\left(t \right)} = 0$$
(the second derivative equals zero),
the roots of this equation will be the inflection points for the specified function graph:
$$\frac{d^{2}}{d t^{2}} f{\left(t \right)} = $$
the second derivative$$- \frac{2 \left(\tan^{2}{\left(\operatorname{atan}{\left(t^{2} \right)} + 1 \right)} + 1\right) \left(- \frac{4 t^{4}}{t^{4} + 1} + \frac{4 t^{2} \tan{\left(\operatorname{atan}{\left(t^{2} \right)} + 1 \right)}}{t^{4} + 1} + 1\right)}{t^{4} + 1} = 0$$
Solve this equationThe roots of this equation
$$t_{1} = -4561.0816054384$$
$$t_{2} = 6557.94206499265$$
$$t_{3} = 2194.45527257084$$
$$t_{4} = -6960.37392835043$$
$$t_{5} = -7178.47419056566$$
$$t_{6} = 4812.99995884256$$
$$t_{7} = -4124.78172456999$$
$$t_{8} = 3285.84467120246$$
$$t_{9} = -1942.21106929836$$
$$t_{10} = 5685.50017306841$$
$$t_{11} = -2815.58612958771$$
$$t_{12} = 3940.40271652102$$
$$t_{13} = 10919.7658075958$$
$$t_{14} = 2849.38413704373$$
$$t_{15} = -4342.93566505384$$
$$t_{16} = -3033.8317153721$$
$$t_{17} = 3722.23025781143$$
$$t_{18} = -2597.31114538297$$
$$t_{19} = 3504.04508557147$$
$$t_{20} = -5433.60462135731$$
$$t_{21} = 9611.25862164469$$
$$t_{22} = 10047.4301664634$$
$$t_{23} = 7430.34617003321$$
$$t_{24} = 8956.99562917743$$
$$t_{25} = 9175.08412196212$$
$$t_{26} = -10449.8277302572$$
$$t_{27} = 6339.83574361643$$
$$t_{28} = -10885.9945779116$$
$$t_{29} = 6776.04606388126$$
$$t_{30} = -1723.6948768428$$
$$t_{31} = -2378.99869523626$$
$$t_{32} = 8738.90622506547$$
$$t_{33} = -10667.9114237547$$
$$t_{34} = -3470.25683552187$$
$$t_{35} = -6524.16738262466$$
$$t_{36} = 8084.63180744039$$
$$t_{37} = -8487.04335987365$$
$$t_{38} = -9359.39985337781$$
$$t_{39} = 8302.72439567443$$
$$t_{40} = -6742.27172393545$$
$$t_{41} = 7866.53797982263$$
$$t_{42} = -3688.44417247294$$
$$t_{43} = 5467.38167722636$$
$$t_{44} = 6121.72685162975$$
$$t_{45} = 7212.24793668016$$
$$t_{46} = -10231.7434629383$$
$$t_{47} = -7832.76494582429$$
$$t_{48} = 4158.56446033742$$
$$t_{49} = -4779.22064019992$$
$$t_{50} = 5249.25917265879$$
$$t_{51} = -7396.57268232278$$
$$t_{52} = 10701.6827335228$$
$$t_{53} = -6306.06068280019$$
$$t_{54} = 5031.13213833407$$
$$t_{55} = -8268.95174565771$$
$$t_{56} = 2631.11413630212$$
$$t_{57} = -9795.57305356333$$
$$t_{58} = 4376.71708985591$$
$$t_{59} = 1757.53994666307$$
$$t_{60} = 6994.14795746859$$
$$t_{61} = -9577.48682614751$$
$$t_{62} = 7648.44280683045$$
$$t_{63} = 9829.34473883156$$
$$t_{64} = -7614.66955569501$$
$$t_{65} = -2160.63746348536$$
$$t_{66} = 2412.80808854532$$
$$t_{67} = 9393.17176688301$$
$$t_{68} = 10483.5991251663$$
$$t_{69} = 1976.04024923119$$
$$t_{70} = 4594.86190201511$$
$$t_{71} = -3252.05380941148$$
$$t_{72} = 10265.5149484802$$
$$t_{73} = -8923.22345322829$$
$$t_{74} = -3906.61844534581$$
$$t_{75} = 8520.81583966705$$
$$t_{76} = -10013.6585843141$$
$$t_{77} = -8705.13390288973$$
$$t_{78} = -5651.72370321664$$
$$t_{79} = -4997.3536728881$$
$$t_{80} = 3067.62576804298$$
$$t_{81} = -8050.8589732138$$
$$t_{82} = -5869.83915653713$$
$$t_{83} = -9141.31208192029$$
$$t_{84} = -6087.95137110257$$
$$t_{85} = 5903.61510426179$$
$$t_{86} = -5215.48145601722$$
Сonvexity and concavity intervals:Let’s find the intervals where the function is convex or concave, for this look at the behaviour of the function at the inflection points:
Have no bends at the whole real axis