In order to find the extrema, we need to solve the equation
$$\frac{d}{d x} f{\left(x \right)} = 0$$
(the derivative equals zero),
and the roots of this equation are the extrema of this function:
$$\frac{d}{d x} f{\left(x \right)} = $$
the first derivative$$- 2 x e^{- x^{2}} \operatorname{erf}{\left(x \right)} + \frac{2 e^{- 2 x^{2}}}{\sqrt{\pi}} = 0$$
Solve this equationThe roots of this equation
$$x_{1} = -42.2332088562321$$
$$x_{2} = -58.1690638483732$$
$$x_{3} = -60.1634415856681$$
$$x_{4} = 22.7028991452193$$
$$x_{5} = -14.6873692419514$$
$$x_{6} = 32.5638726903793$$
$$x_{7} = -94.1043957123074$$
$$x_{8} = 24.6661073409247$$
$$x_{9} = 36.5294784207713$$
$$x_{10} = -72.1362492686553$$
$$x_{11} = 18.7999073667175$$
$$x_{12} = 90.362564912866$$
$$x_{13} = 74.3867866673358$$
$$x_{14} = -68.1442499509512$$
$$x_{15} = 88.365113164645$$
$$x_{16} = 80.3765739119403$$
$$x_{17} = -28.3487957849917$$
$$x_{18} = 0.620062633313595$$
$$x_{19} = -24.4061660554474$$
$$x_{20} = 64.408034863895$$
$$x_{21} = 100.254985258958$$
$$x_{22} = -36.2718473606153$$
$$x_{23} = 14.9488147933141$$
$$x_{24} = 78.3798045164052$$
$$x_{25} = 66.4032735361933$$
$$x_{26} = 62.4131011494136$$
$$x_{27} = 52.4442259550818$$
$$x_{28} = 50.4519304520445$$
$$x_{29} = 98.2550892572402$$
$$x_{30} = -6.06604483174545$$
$$x_{31} = -64.1532478546075$$
$$x_{32} = 92.3601269622654$$
$$x_{33} = 84.3705719720027$$
$$x_{34} = 70.3945619595659$$
$$x_{35} = 11.204731998154$$
$$x_{36} = -96.1022227575382$$
$$x_{37} = -16.6040954166054$$
$$x_{38} = -18.5386580960287$$
$$x_{39} = 42.4899960942614$$
$$x_{40} = 44.4791976169932$$
$$x_{41} = -40.244810563854$$
$$x_{42} = -48.2041698444887$$
$$x_{43} = 26.6348104846935$$
$$x_{44} = -88.111506182266$$
$$x_{45} = 72.3905669642191$$
$$x_{46} = -26.3753139220651$$
$$x_{47} = 7.73387960889725$$
$$x_{48} = 38.5149532926537$$
$$x_{49} = 30.5844367675871$$
$$x_{50} = -10.9467267431996$$
$$x_{51} = -62.1581808370582$$
$$x_{52} = 96.3555548022907$$
$$x_{53} = -46.2130128196551$$
$$x_{54} = -76.129088844583$$
$$x_{55} = -44.2226547762937$$
$$x_{56} = 6.2599967922195$$
$$x_{57} = -98.0051017678288$$
$$x_{58} = 16.8656081194959$$
$$x_{59} = 76.3832042269081$$
$$x_{60} = -56.1750861644869$$
$$x_{61} = -7.49944089361232$$
$$x_{62} = -92.1066629479709$$
$$x_{63} = 60.4185026243398$$
$$x_{64} = -22.4425007185933$$
$$x_{65} = 28.6078690007847$$
$$x_{66} = -70.1401356046363$$
$$x_{67} = 9.41469724573827$$
$$x_{68} = -50.1960306485386$$
$$x_{69} = -84.1168098950626$$
$$x_{70} = -9.16348321175021$$
$$x_{71} = 86.3677793889685$$
$$x_{72} = 82.3735001099731$$
$$x_{73} = -66.1486129602884$$
$$x_{74} = -12.7968091698462$$
$$x_{75} = 48.4602702583442$$
$$x_{76} = 34.5456823438052$$
$$x_{77} = -78.125783449603$$
$$x_{78} = -80.122642994584$$
$$x_{79} = -30.3257619544685$$
$$x_{80} = -82.119655441293$$
$$x_{81} = 46.4693271688763$$
$$x_{82} = -38.2576235616253$$
$$x_{83} = -34.2877276681532$$
$$x_{84} = 54.4370869389189$$
$$x_{85} = -86.1140964733663$$
$$x_{86} = -52.1885145543938$$
$$x_{87} = 40.5018595731864$$
$$x_{88} = -90.1090308486583$$
$$x_{89} = -74.132572514098$$
$$x_{90} = -54.1815527450525$$
$$x_{91} = 58.4242736475066$$
$$x_{92} = 20.7467570641594$$
$$x_{93} = -100.005001054049$$
$$x_{94} = 56.4304534331944$$
$$x_{95} = 13.0574223701178$$
$$x_{96} = 68.3987904608748$$
$$x_{97} = 94.3577924641168$$
$$x_{98} = -32.3055705254499$$
$$x_{99} = -20.4859087535338$$
The values of the extrema at the points:
(-42.23320885623211, -2.36201903422506e-775)
(-58.169063848373206, -3.19024496418379e-1470)
(-60.16344158566805, -1.02435459878317e-1572)
(22.702899145219273, 1.42965224969698e-224)
(-14.687369241951417, -2.06304591862193e-94)
(32.56387269037934, 2.96217345735766e-461)
(-94.10439571230735, -1.11068315011957e-3846)
(24.66610734092469, 5.86028530581723e-265)
(36.52947842077126, 2.99385017487423e-580)
(-72.13624926865535, -1.22611620511294e-2260)
(18.799907366717463, 3.19500075432685e-154)
(90.36256491286605, 6.52856535115721e-3547)
(74.3867866673358, 7.54234292083798e-2404)
(-68.14424995095123, -1.96468355427716e-2017)
(88.36511316464497, 7.20958099577641e-3392)
(80.37657391194027, 1.93505765072647e-2806)
(-28.348795784991665, -9.49305129893489e-350)
(0.6200626333135955, 0.421731890755712)
(-24.406166055447407, -2.03114070602669e-259)
(64.40803486389501, 2.37116772922016e-1802)
(100.25498525895824, 7.57192053017521e-4366)
(-36.27184736061533, -4.18606955847268e-572)
(14.948814793314096, 8.90199481918394e-98)
(78.37980451640516, 9.07802965957446e-2669)
(66.40327353619331, 1.0572981733366e-1915)
(62.41310114941363, 1.78386482221949e-1692)
(52.44422595508178, 3.29481526196589e-1195)
(50.45193045204447, 3.53186660149504e-1106)
(98.25508925724017, 1.96743364617912e-4193)
(-6.0660448317454545, -1.04546481666534e-16)
(-64.15324785460746, -3.98658900238342e-1788)
(92.36012696226535, 1.9832106209079e-3705)
(84.37057197200274, 3.31909665718435e-3092)
(70.3945619595659, 7.93554263796515e-2153)
(11.204731998153951, 2.99265503277496e-55)
(-96.10222275753824, -1.03209328933537e-4011)
(-16.604095416605446, -1.84822654602712e-120)
(-18.53865809602872, -5.50644898269458e-150)
(42.489996094261436, 8.41091199611194e-785)
(44.47919761699318, 6.19758266540941e-860)
(-40.24481056385404, -3.95558358784209e-704)
(-48.204169844488675, -7.16317649879776e-1010)
(26.634810484693503, 8.04993631018709e-309)
(-88.11150618226596, -1.97271717373501e-3372)
(72.39056696421908, 1.33574107923126e-2276)
(-26.37531392206507, -7.58443931412971e-303)
(7.733879608897252, 1.05582094677417e-26)
(38.5149532926537, 5.84600104745273e-645)
(30.58443676758709, 5.72224069192688e-407)
(-10.94672674319965, -9.08099291404701e-53)
(-62.15818083705824, -1.10333903852353e-1678)
(96.35555480229068, 6.9084050103552e-4033)
(-46.21301281965513, -3.17850966733066e-928)
(-76.12908884458302, -9.69001382462453e-2518)
(-44.22265477629371, -4.73098573623154e-850)
(6.259996792219498, 9.57324123622751e-18)
(-98.00510176782878, -3.99496751864527e-4172)
(16.865608119495942, 2.92067364744978e-124)
(76.38320422690806, 1.4286610505639e-2534)
(-56.175086164486885, -3.33294703233584e-1371)
(-7.4994408936123165, -3.754719597773e-25)
(-92.10666294797095, -4.00966730656896e-3685)
(60.41850262433981, 4.50189365823445e-1586)
(-22.442500718593337, -1.82265979785087e-219)
(28.607869000784714, 3.70663456583788e-356)
(-70.14013560463634, -2.67974352817363e-2137)
(9.414697245738271, 3.2036615750287e-39)
(-50.19603064853855, -5.41505999314516e-1095)
(-84.11680989506259, -1.2291020333813e-3073)
(-9.163483211750211, -3.40833488579871e-37)
(86.36777938896853, 2.67081780406478e-3240)
(82.37350010997311, 1.38368286300953e-2947)
(-66.14861296028836, -4.83202295697936e-1901)
(-12.796809169846151, -7.59736719916995e-72)
(48.46027025834418, 1.2699802411106e-1020)
(34.54568234380517, 5.14227024991919e-519)
(-78.12578344960298, -1.67370865040539e-2651)
(-80.12264299458401, -9.69784720094796e-2789)
(-30.325761954468536, -3.98365236656537e-400)
(-82.11965544129303, -1.88499955131508e-2929)
(46.46932716887627, 1.53180947552826e-938)
(-38.2576235616253, -2.22189083575109e-636)
(-34.28772766815322, -2.64511323277732e-511)
(54.437086938918874, 1.03105266780508e-1287)
(-86.11409647336635, -2.6884722879124e-3221)
(-52.18851455439384, -1.37315857828959e-1183)
(40.50185957318639, 3.82876546618973e-713)
(-90.1090308486583, -4.85584194845144e-3527)
(-74.13257251409804, -1.88195177929612e-2387)
(-54.181552745052464, -1.16805001261165e-1275)
(58.42427364750664, 3.8111907435675e-1483)
(20.746757064159397, 1.16822290630728e-187)
(-100.00500105404947, -4.1762267425666e-4344)
(56.430453433194394, 1.08232221825114e-1383)
(13.057422370117813, 9.00340665465327e-75)
(68.39879046087482, 1.58149792740942e-2032)
(94.35779246411681, 2.02092617060776e-3867)
(-32.30557052544994, -5.60548310429432e-454)
(-20.485908753533757, -5.47731249366018e-183)
Intervals of increase and decrease of the function:Let's find intervals where the function increases and decreases, as well as minima and maxima of the function, for this let's look how the function behaves itself in the extremas and at the slightest deviation from:
The function has no minima
Maxima of the function at points:
$$x_{99} = 0.620062633313595$$
Decreasing at intervals
$$\left(-\infty, 0.620062633313595\right]$$
Increasing at intervals
$$\left[0.620062633313595, \infty\right)$$