El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\left|{\sin{\left(4 x \right)}}\right| = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = 0$$
$$x_{2} = \frac{\pi}{4}$$
Solución numérica$$x_{1} = -59.6902604182061$$
$$x_{2} = 68.329640215578$$
$$x_{3} = 87.9645943005142$$
$$x_{4} = -55.7632696012188$$
$$x_{5} = 98.174770424681$$
$$x_{6} = -37.6991118430775$$
$$x_{7} = -91.8915851175014$$
$$x_{8} = 95.8185759344887$$
$$x_{9} = -81.6814089933346$$
$$x_{10} = -33.7721210260903$$
$$x_{11} = -21.9911485751286$$
$$x_{12} = -15.707963267949$$
$$x_{13} = -18.0641577581413$$
$$x_{14} = -27.4889357189107$$
$$x_{15} = -87.9645943005142$$
$$x_{16} = 72.2566310325652$$
$$x_{17} = -11.7809724509617$$
$$x_{18} = 25.9181393921158$$
$$x_{19} = -40.0553063332699$$
$$x_{20} = 3.92699081698724$$
$$x_{21} = 91.8915851175014$$
$$x_{22} = 80.1106126665397$$
$$x_{23} = 6.28318530717959$$
$$x_{24} = 46.3384916404494$$
$$x_{25} = 10.9955742875643$$
$$x_{26} = -51.8362787842316$$
$$x_{27} = -99.7455667514759$$
$$x_{28} = 65.9734457253857$$
$$x_{29} = 0$$
$$x_{30} = -25.1327412287183$$
$$x_{31} = 10.2101761241668$$
$$x_{32} = 11.7809724509617$$
$$x_{33} = 24.3473430653209$$
$$x_{34} = -73.8274273593601$$
$$x_{35} = -43.9822971502571$$
$$x_{36} = 96.6039740978861$$
$$x_{37} = -77.7544181763474$$
$$x_{38} = 54.1924732744239$$
$$x_{39} = 43.9822971502571$$
$$x_{40} = 76.1836218495525$$
$$x_{41} = -65.9734457253857$$
$$x_{42} = 36.9137136796801$$
$$x_{43} = 69.9004365423729$$
$$x_{44} = -95.8185759344887$$
$$x_{45} = -62.0464549083984$$
$$x_{46} = -84.037603483527$$
$$x_{47} = -72.2566310325652$$
$$x_{48} = 28.2743338823081$$
$$x_{49} = 90.3207887907066$$
$$x_{50} = 21.9911485751286$$
$$x_{51} = 50.2654824574367$$
$$x_{52} = -80.1106126665397$$
$$x_{53} = 94.2477796076938$$
$$x_{54} = 32.2013246992954$$
$$x_{55} = 47.9092879672443$$
$$x_{56} = -7.06858347057703$$
$$x_{57} = -58.1194640914112$$
$$x_{58} = 83.2522053201295$$