El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$- 2 \cos{\left(2 x - \frac{\pi}{4} \right)} - 1 = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = - \frac{5 \pi}{24}$$
$$x_{2} = \frac{11 \pi}{24}$$
Solución numérica$$x_{1} = 18.1950574520409$$
$$x_{2} = 17.1478599008443$$
$$x_{3} = -1.70169602069447$$
$$x_{4} = 14.0062672472545$$
$$x_{5} = 89.4044909334095$$
$$x_{6} = -44.636795619755$$
$$x_{7} = 4.58148928648512$$
$$x_{8} = -33.1176225565924$$
$$x_{9} = 49.6109839879388$$
$$x_{10} = -16.3624617374468$$
$$x_{11} = -3.79609112308767$$
$$x_{12} = 33.9030207199899$$
$$x_{13} = -39.400807863772$$
$$x_{14} = 76.8381203190504$$
$$x_{15} = -95.9494756283883$$
$$x_{16} = -105.374253589158$$
$$x_{17} = 84.1685031774265$$
$$x_{18} = 93.5932811381959$$
$$x_{19} = -73.9583270532597$$
$$x_{20} = 92.5460835869993$$
$$x_{21} = 55.8941692951184$$
$$x_{22} = 77.885317870247$$
$$x_{23} = -23.692844595823$$
$$x_{24} = -198.574835645655$$
$$x_{25} = 2.48709418409192$$
$$x_{26} = -82.3359074628325$$
$$x_{27} = -11.1264739814639$$
$$x_{28} = 7.72308194007491$$
$$x_{29} = 73.6965276654606$$
$$x_{30} = -66.6279441948835$$
$$x_{31} = 20.2894525544341$$
$$x_{32} = -51.9671784781312$$
$$x_{33} = -0.654498469497874$$
$$x_{34} = -83.3831050140291$$
$$x_{35} = -76.0527221556529$$
$$x_{36} = -45.6839931709516$$
$$x_{37} = -98.0438707307815$$
$$x_{38} = 54.8469717439218$$
$$x_{39} = 35.997415822383$$
$$x_{40} = -69.7695368484733$$
$$x_{41} = 46.469391334349$$
$$x_{42} = 10.8646745936647$$
$$x_{43} = -10.0792764302673$$
$$x_{44} = 51.705379090332$$
$$x_{45} = -25.7872396982162$$
$$x_{46} = 86.2628982798197$$
$$x_{47} = 43.3277986807592$$
$$x_{48} = -80.2415123604393$$
$$x_{49} = -91.7606854236019$$
$$x_{50} = 26.5726378616137$$
$$x_{51} = -14.2680666350536$$
$$x_{52} = 11.9118721448613$$
$$x_{53} = 71.6021325630674$$
$$x_{54} = -19.5040543910366$$
$$x_{55} = 90.4516884846061$$
$$x_{56} = -38.3536103125754$$
$$x_{57} = 98.8292688941789$$
$$x_{58} = -60.3447588877039$$
$$x_{59} = 3045.6431779614$$
$$x_{60} = 48.5637864367422$$
$$x_{61} = -77.0999197068495$$
$$x_{62} = -32.0704250053958$$
$$x_{63} = -99.0910682819781$$
$$x_{64} = -17.4096592886434$$
$$x_{65} = -29.9760299030026$$
$$x_{66} = 79.9797129726402$$
$$x_{67} = 42.2806011295626$$
$$x_{68} = 27.6198354128103$$
$$x_{69} = -88.6190927700121$$
$$x_{70} = -61.3919564389005$$
$$x_{71} = 99.8764664453755$$
$$x_{72} = -58.2503637853107$$
$$x_{73} = -7.98488132787406$$
$$x_{74} = 62.177354602298$$
$$x_{75} = -89.6662903212087$$
$$x_{76} = 29.7142305152035$$
$$x_{77} = -85.4775001164223$$
$$x_{78} = 32.8558231687933$$
$$x_{79} = -36.2592152101822$$
$$x_{80} = -67.6751417460801$$
$$x_{81} = 24.4782427592205$$
$$x_{82} = -55.108771131721$$
$$x_{83} = 57.9885643975116$$
$$x_{84} = 40.1862060271694$$
$$x_{85} = 21.3366501056307$$
$$x_{86} = 64.2717497046912$$
$$x_{87} = 68.4605399094776$$
$$x_{88} = 5.62868683768171$$
$$x_{89} = -22.6456470446264$$
$$x_{90} = -47.7783882733448$$
$$x_{91} = -41.4952029661652$$
$$x_{92} = -54.0615735805244$$
$$x_{93} = -63.4863515412937$$
$$x_{94} = 70.5549350118708$$
$$x_{95} = 95.6876762405891$$