Hallemos los puntos de flexiones, para eso hay que resolver la ecuación
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = 0$$
(la segunda derivada es igual a cero),
las raíces de la ecuación obtenida serán los puntos de flexión para el gráfico de la función indicado:
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = $$
segunda derivada$$\frac{2 \left(2 \left(\cos{\left(\pi x \right)} - \frac{\sin{\left(\pi x \right)}}{\pi x}\right)^{2} - \left(\cos{\left(\pi x \right)} - \frac{\sin{\left(\pi x \right)}}{\pi x}\right) \cos{\left(\pi x \right)} - \frac{\left(\pi \sin{\left(\pi x \right)} + \frac{2 \cos{\left(\pi x \right)}}{x} - \frac{2 \sin{\left(\pi x \right)}}{\pi x^{2}}\right) \sin{\left(\pi x \right)}}{\pi} + \frac{\left(\cos{\left(\pi x \right)} - \frac{\sin{\left(\pi x \right)}}{\pi x}\right) \sin{\left(\pi x \right)}}{\pi x}\right)}{x^{2}} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -61.7483527761947$$
$$x_{2} = -81.7487569556855$$
$$x_{3} = -83.7487867257144$$
$$x_{4} = -99.7489818056511$$
$$x_{5} = -7.73649601515403$$
$$x_{6} = -77.7486928066096$$
$$x_{7} = -95.7489391632373$$
$$x_{8} = 90.2488802811355$$
$$x_{9} = -87.748842183449$$
$$x_{10} = -69.7485423590771$$
$$x_{11} = 100.248991709865$$
$$x_{12} = 52.2480696155498$$
$$x_{13} = -89.7488680535879$$
$$x_{14} = -29.7465664532108$$
$$x_{15} = 80.2487411636708$$
$$x_{16} = 74.2486397633915$$
$$x_{17} = 4.22735950767312$$
$$x_{18} = 70.2485625726606$$
$$x_{19} = 18.2445188624812$$
$$x_{20} = -57.7482382050547$$
$$x_{21} = 2.20888752467459$$
$$x_{22} = 24.2458621171043$$
$$x_{23} = -9.7393399929161$$
$$x_{24} = 36.2472230924613$$
$$x_{25} = -79.7487256879633$$
$$x_{26} = 98.2489712343711$$
$$x_{27} = -31.7467844060814$$
$$x_{28} = 30.2466765477645$$
$$x_{29} = -75.7486581834026$$
$$x_{30} = -17.744212784795$$
$$x_{31} = 96.2489499100364$$
$$x_{32} = -67.7484991757802$$
$$x_{33} = -15.7434662299526$$
$$x_{34} = 28.2464431968423$$
$$x_{35} = -41.7475591015791$$
$$x_{36} = 40.2474974528301$$
$$x_{37} = 12.2418838185292$$
$$x_{38} = 72.2486022329285$$
$$x_{39} = 10.2403346426075$$
$$x_{40} = 22.2454940358069$$
$$x_{41} = -37.7472987956897$$
$$x_{42} = -63.7484046496571$$
$$x_{43} = -73.7486216761659$$
$$x_{44} = 58.2482676493225$$
$$x_{45} = 92.2489044945726$$
$$x_{46} = -55.7481747273539$$
$$x_{47} = -25.746028000833$$
$$x_{48} = -27.746316803873$$
$$x_{49} = 32.2468811632873$$
$$x_{50} = 42.2476152591584$$
$$x_{51} = -13.7424984608719$$
$$x_{52} = 26.2461745995811$$
$$x_{53} = 44.2477224724436$$
$$x_{54} = -23.7456900482187$$
$$x_{55} = -19.7448062051182$$
$$x_{56} = 6.23436247448923$$
$$x_{57} = -21.7452892305997$$
$$x_{58} = -65.7484533556792$$
$$x_{59} = -33.7469763389274$$
$$x_{60} = 14.2430048647492$$
$$x_{61} = 64.2484288313613$$
$$x_{62} = -45.7477736462445$$
$$x_{63} = 38.2473674018583$$
$$x_{64} = 50.2479931440213$$
$$x_{65} = -49.7479535220692$$
$$x_{66} = -85.748815103141$$
$$x_{67} = 88.2488549731412$$
$$x_{68} = 94.2489276829586$$
$$x_{69} = -91.7488927929056$$
$$x_{70} = 84.2488007625499$$
$$x_{71} = -51.7480329833019$$
$$x_{72} = 20.2450540655959$$
$$x_{73} = 8.23805394372117$$
$$x_{74} = -59.7482974159256$$
$$x_{75} = 48.2479103636241$$
$$x_{76} = 54.2481404729683$$
$$x_{77} = -11.7411939995098$$
$$x_{78} = 66.2484760938889$$
$$x_{79} = -47.7478673704273$$
$$x_{80} = 60.248324929728$$
$$x_{81} = 82.2487716856391$$
$$x_{82} = -39.747435537556$$
$$x_{83} = 78.2487090861744$$
$$x_{84} = -71.7485831268165$$
$$x_{85} = 46.2478204600269$$
$$x_{86} = 16.2438537460501$$
$$x_{87} = -5.73157811771419$$
$$x_{88} = 62.2483785433487$$
$$x_{89} = 56.2482063126328$$
$$x_{90} = -93.7489164739615$$
$$x_{91} = 68.2485205959957$$
$$x_{92} = -97.7489609217602$$
$$x_{93} = -43.747671305176$$
$$x_{94} = 76.2486753311251$$
$$x_{95} = -35.7471466490446$$
$$x_{96} = 34.2470620436327$$
$$x_{97} = -53.7481065043619$$
$$x_{98} = -1.68100482418311$$
$$x_{99} = -3.72099743965763$$
$$x_{100} = 86.2488284946546$$
Además hay que calcular los límites de y'' para los argumentos tendientes a los puntos de indeterminación de la función:
Puntos donde hay indeterminación:
$$x_{1} = 0$$
$$\lim_{x \to 0^-}\left(\frac{2 \left(2 \left(\cos{\left(\pi x \right)} - \frac{\sin{\left(\pi x \right)}}{\pi x}\right)^{2} - \left(\cos{\left(\pi x \right)} - \frac{\sin{\left(\pi x \right)}}{\pi x}\right) \cos{\left(\pi x \right)} - \frac{\left(\pi \sin{\left(\pi x \right)} + \frac{2 \cos{\left(\pi x \right)}}{x} - \frac{2 \sin{\left(\pi x \right)}}{\pi x^{2}}\right) \sin{\left(\pi x \right)}}{\pi} + \frac{\left(\cos{\left(\pi x \right)} - \frac{\sin{\left(\pi x \right)}}{\pi x}\right) \sin{\left(\pi x \right)}}{\pi x}\right)}{x^{2}}\right) = - \frac{2 \pi^{2}}{3}$$
$$\lim_{x \to 0^+}\left(\frac{2 \left(2 \left(\cos{\left(\pi x \right)} - \frac{\sin{\left(\pi x \right)}}{\pi x}\right)^{2} - \left(\cos{\left(\pi x \right)} - \frac{\sin{\left(\pi x \right)}}{\pi x}\right) \cos{\left(\pi x \right)} - \frac{\left(\pi \sin{\left(\pi x \right)} + \frac{2 \cos{\left(\pi x \right)}}{x} - \frac{2 \sin{\left(\pi x \right)}}{\pi x^{2}}\right) \sin{\left(\pi x \right)}}{\pi} + \frac{\left(\cos{\left(\pi x \right)} - \frac{\sin{\left(\pi x \right)}}{\pi x}\right) \sin{\left(\pi x \right)}}{\pi x}\right)}{x^{2}}\right) = - \frac{2 \pi^{2}}{3}$$
- los límites son iguales, es decir omitimos el punto correspondiente
Intervalos de convexidad y concavidad:Hallemos los intervales donde la función es convexa o cóncava, para eso veamos cómo se comporta la función en los puntos de flexiones:
Cóncava en los intervalos
$$\left(-\infty, -99.7489818056511\right]$$
Convexa en los intervalos
$$\left[100.248991709865, \infty\right)$$