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$$\frac{\pi \frac{1}{\pi x} \cos{\left(x \frac{\pi}{2} \right)}}{2} - \frac{\sin{\left(x \frac{\pi}{2} \right)}}{\pi x^{2}} = 0$$
Solve this equationThe roots of this equation
$$x_{1} = 32.9877155958269$$
$$x_{2} = -86.9953413884714$$
$$x_{3} = 86.9953413884714$$
$$x_{4} = 36.9890441958502$$
$$x_{5} = 68.994125974822$$
$$x_{6} = -46.9913758655731$$
$$x_{7} = 30.9869226211336$$
$$x_{8} = -76.9947363220078$$
$$x_{9} = -102.996065096535$$
$$x_{10} = 56.9928891501073$$
$$x_{11} = -90.9955461762757$$
$$x_{12} = 64.9937644514483$$
$$x_{13} = 80.9949962786911$$
$$x_{14} = -146.997242926516$$
$$x_{15} = 44.9909924705645$$
$$x_{16} = 34.9884178810314$$
$$x_{17} = 90.9955461762757$$
$$x_{18} = 40.9901134171449$$
$$x_{19} = 58.9931302339508$$
$$x_{20} = 98.9959061019405$$
$$x_{21} = 130.996906174689$$
$$x_{22} = -22.9823699155424$$
$$x_{23} = 728.999444053579$$
$$x_{24} = 42.9905733959369$$
$$x_{25} = 240.99831831278$$
$$x_{26} = 78.994869591368$$
$$x_{27} = 8.95481716686503$$
$$x_{28} = 96.995821686872$$
$$x_{29} = 74.9945959439502$$
$$x_{30} = -112.996413333534$$
$$x_{31} = -8.95481716686503$$
$$x_{32} = 54.9926305283549$$
$$x_{33} = 12.9687742527727$$
$$x_{34} = 6.94177944869404$$
$$x_{35} = -2.86059330624841$$
$$x_{36} = -370.998907586172$$
$$x_{37} = 2.86059330624841$$
$$x_{38} = -690.999413480515$$
$$x_{39} = 62.993566470984$$
$$x_{40} = -70.9942914583172$$
$$x_{41} = 38.9896062370735$$
$$x_{42} = -1000.99959512004$$
$$x_{43} = -82.9951168598645$$
$$x_{44} = -32.9877155958269$$
$$x_{45} = 102.996065096535$$
$$x_{46} = 26.9849838868809$$
$$x_{47} = 94.995733717172$$
$$x_{48} = 66.9939506099815$$
$$x_{49} = -168.997601842789$$
$$x_{50} = 46.9913758655731$$
$$x_{51} = -104.996140050787$$
$$x_{52} = 4.91804806591352$$
$$x_{53} = -74.9945959439502$$
$$x_{54} = 50.9920524148283$$
$$x_{55} = -2596.99984394118$$
$$x_{56} = 1940.99979119796$$
$$x_{57} = -12.9687742527727$$
$$x_{58} = -48.9917279519966$$
$$x_{59} = 70.9942914583172$$
$$x_{60} = 76.9947363220078$$
$$x_{61} = 100.995987173567$$
$$x_{62} = -64.9937644514483$$
$$x_{63} = 72.9944478728046$$
$$x_{64} = 52.9923523825456$$
$$x_{65} = 28.986020171625$$
$$x_{66} = 10.9630733012144$$
$$x_{67} = 84.9952317659775$$
$$x_{68} = -10.9630733012144$$
$$x_{69} = 82.9951168598645$$
$$x_{70} = -100.995987173567$$
$$x_{71} = -238.998304239951$$
$$x_{72} = -496.999184536865$$
$$x_{73} = 60.9933555054535$$
$$x_{74} = -80.9949962786911$$
$$x_{75} = -118.996594180944$$
$$x_{76} = -4.91804806591352$$
$$x_{77} = 88.9954460835957$$
$$x_{78} = 24.9837815964593$$
$$x_{79} = -62.993566470984$$
$$x_{80} = -40.9901134171449$$
$$x_{81} = -72.9944478728046$$
$$x_{82} = -56.9928891501073$$
$$x_{83} = 92.9956419634817$$
$$x_{84} = 48.9917279519966$$
The values of the extrema at the points:
0.0303143149483956*sin(0.493857797913467*pi)
(32.987715595826934, --------------------------------------------)
pi 0.0114948683922576*sin(1.49767069423572*pi)
(-86.99534138847145, -------------------------------------------)
pi 0.0114948683922576*sin(1.49767069423572*pi)
(86.99534138847145, -------------------------------------------)
pi 0.0270350321761542*sin(0.494522097925103*pi)
(36.989044195850205, --------------------------------------------)
pi 0.0144939875079355*sin(0.497062987410978*pi)
(68.99412597482196, --------------------------------------------)
pi 0.021280500551009*sin(1.49568793278657*pi)
(-46.99137586557314, ------------------------------------------)
pi 0.0322716783536931*sin(1.49346131056681*pi)
(30.986922621133623, -------------------------------------------)
pi 0.0129879008328283*sin(0.497368161003912*pi)
(-76.99473632200782, --------------------------------------------)
pi 0.00970910878063864*sin(1.49803254826764*pi)
(-102.99606509653528, --------------------------------------------)
pi 0.0175460485494289*sin(0.496444575053626*pi)
(56.99288915010725, --------------------------------------------)
pi 0.0109895488517956*sin(1.49777308813785*pi)
(-90.9955461762757, -------------------------------------------)
pi 0.0153860913956911*sin(0.496882225724129*pi)
(64.99376445144826, --------------------------------------------)
pi 0.0123464417055982*sin(0.497498139345559*pi)
(80.99499627869112, --------------------------------------------)
pi 0.00680284867995724*sin(1.49862146325782*pi)
(-146.99724292651564, --------------------------------------------)
pi 0.0222266712754615*sin(0.495496235282229*pi)
(44.99099247056446, --------------------------------------------)
pi 0.0285808864922166*sin(1.49420894051568*pi)
(34.98841788103136, -------------------------------------------)
pi 0.0109895488517956*sin(1.49777308813785*pi)
(90.9955461762757, -------------------------------------------)
pi 0.0243961266909237*sin(0.495056708572449*pi)
(40.9901134171449, --------------------------------------------)
pi 0.016951126275793*sin(1.49656511697539*pi)
(58.99313023395077, ------------------------------------------)
pi 0.0101014278203611*sin(1.49795305097026*pi)
(98.99590610194052, -------------------------------------------)
pi 0.00763376807286169*sin(1.49845308734453*pi)
(130.99690617468906, --------------------------------------------)
pi 0.0435116136270926*sin(1.49118495777122*pi)
(-22.982369915542446, -------------------------------------------)
pi 0.00137174315859492*sin(0.499722026789698*pi)
(728.9994440535794, ---------------------------------------------)
pi 0.0232609132888307*sin(1.49528669796846*pi)
(42.99057339593692, -------------------------------------------)
pi 0.00414940654773428*sin(0.499159156390149*pi)
(240.9983183127803, ---------------------------------------------)
pi 0.012659049950622*sin(1.49743479568401*pi)
(78.99486959136802, ------------------------------------------)
pi 0.111671738391292*sin(0.477408583432515*pi)
(8.95481716686503, -------------------------------------------)
pi 0.0103097224458623*sin(0.497910843435982*pi)
(96.99582168687196, --------------------------------------------)
pi 0.0133342941236377*sin(1.49729797197509*pi)
(74.99459594395017, -------------------------------------------)
pi 0.00884983841963443*sin(0.498206666766912*pi)
(-112.99641333353382, ---------------------------------------------)
pi 0.111671738391292*sin(0.477408583432515*pi)
(-8.95481716686503, -------------------------------------------)
pi 0.0181842546972614*sin(1.49631526417743*pi)
(54.992630528354866, -------------------------------------------)
pi 0.0771082895352429*sin(0.484387126386342*pi)
(12.968774252772684, --------------------------------------------)
pi 0.144055282567084*sin(1.47088972434702*pi)
(6.94177944869404, ------------------------------------------)
pi 0.349577829821421*sin(1.4302966531242*pi)
(-2.8605933062484055, -----------------------------------------)
pi 0.00269542572646991*sin(1.49945379308605*pi)
(-370.9989075861721, --------------------------------------------)
pi 0.349577829821421*sin(1.4302966531242*pi)
(2.8605933062484055, -----------------------------------------)
pi 0.00144717923125733*sin(1.49970674025769*pi)
(-690.9994134805154, --------------------------------------------)
pi 0.0158746369831373*sin(1.49678323549202*pi)
(62.993566470984035, -------------------------------------------)
pi 0.0140856395557821*sin(1.49714572915862*pi)
(-70.99429145831724, -------------------------------------------)
pi 0.0256478609688842*sin(1.49480311853674*pi)
(38.989606237073474, -------------------------------------------)
pi 0.000999001403072579*sin(0.499797560018067*pi)
(-1000.9995951200361, ----------------------------------------------)
pi 0.0120489016442796*sin(1.49755842993227*pi)
(-82.99511685986454, -------------------------------------------)
pi 0.0303143149483956*sin(0.493857797913467*pi)
(-32.987715595826934, --------------------------------------------)
pi 0.00970910878063864*sin(1.49803254826764*pi)
(102.99606509653528, --------------------------------------------)
pi 0.0370576467338995*sin(1.49249194344043*pi)
(26.984983886880855, -------------------------------------------)
pi 0.0105267885290225*sin(1.49786685858598*pi)
(94.99573371717196, -------------------------------------------)
pi 0.0149267208590474*sin(1.49697530499073*pi)
(66.99395060998145, -------------------------------------------)
pi 0.00591724373065516*sin(0.498800921394462*pi)
(-168.99760184278892, ---------------------------------------------)
pi 0.021280500551009*sin(1.49568793278657*pi)
(46.99137586557314, ------------------------------------------)
pi 0.00952415964545265*sin(0.49807002539351*pi)
(-104.99614005078702, --------------------------------------------)
pi 0.20333270163236*sin(0.459024032956761*pi)
(4.918048065913522, ------------------------------------------)
pi 0.0133342941236377*sin(1.49729797197509*pi)
(-74.99459594395017, -------------------------------------------)
pi 0.019610899201798*sin(1.49602620741414*pi)
(50.99205241482829, ------------------------------------------)
pi 0.000385059707390051*sin(0.499921970591004*pi)
(-2596.999843941182, ----------------------------------------------)
pi 0.00051519840678747*sin(0.499895598978924*pi)
(1940.9997911979578, ---------------------------------------------)
pi 0.0771082895352429*sin(0.484387126386342*pi)
(-12.968774252772684, --------------------------------------------)
pi 0.0204116090981691*sin(0.495863975998319*pi)
(-48.99172795199664, --------------------------------------------)
pi 0.0140856395557821*sin(1.49714572915862*pi)
(70.99429145831724, -------------------------------------------)
pi 0.0129879008328283*sin(0.497368161003912*pi)
(76.99473632200782, --------------------------------------------)
pi 0.00990138349042965*sin(0.497993586783473*pi)
(100.99598717356695, ---------------------------------------------)
pi 0.0153860913956911*sin(0.496882225724129*pi)
(-64.99376445144826, --------------------------------------------)
pi 0.0136996720866022*sin(0.497223936402321*pi)
(72.99444787280464, --------------------------------------------)
pi 0.0188706474621303*sin(0.496176191272795*pi)
(52.99235238254559, --------------------------------------------)
pi 0.0344993895015267*sin(0.493010085812484*pi)
(28.98602017162497, --------------------------------------------)
pi 0.0912152981672784*sin(1.4815366506072*pi)
(10.963073301214392, ------------------------------------------)
pi 0.0117653658825634*sin(0.497615882988754*pi)
(84.99523176597751, --------------------------------------------)
pi 0.0912152981672784*sin(1.4815366506072*pi)
(-10.963073301214392, ------------------------------------------)
pi 0.0120489016442796*sin(1.49755842993227*pi)
(82.99511685986454, -------------------------------------------)
pi 0.00990138349042965*sin(0.497993586783473*pi)
(-100.99598717356695, ---------------------------------------------)
pi 0.00418413010577687*sin(1.49915211997566*pi)
(-238.99830423995132, --------------------------------------------)
pi 0.00201207573596295*sin(0.499592268432707*pi)
(-496.9991845368654, ---------------------------------------------)
pi 0.0163952284919066*sin(0.496677752726768*pi)
(60.993355505453536, --------------------------------------------)
pi 0.0123464417055982*sin(0.497498139345559*pi)
(-80.99499627869112, --------------------------------------------)
pi 0.00840360185838106*sin(1.49829709047214*pi)
(-118.99659418094427, --------------------------------------------)
pi 0.20333270163236*sin(0.459024032956761*pi)
(-4.918048065913522, ------------------------------------------)
pi 0.0112365300024529*sin(0.497723041797855*pi)
(88.99544608359571, --------------------------------------------)
pi 0.0400259662909365*sin(0.491890798229646*pi)
(24.98378159645929, --------------------------------------------)
pi 0.0158746369831373*sin(1.49678323549202*pi)
(-62.993566470984035, -------------------------------------------)
pi 0.0243961266909237*sin(0.495056708572449*pi)
(-40.9901134171449, --------------------------------------------)
pi 0.0136996720866022*sin(0.497223936402321*pi)
(-72.99444787280464, --------------------------------------------)
pi 0.0175460485494289*sin(0.496444575053626*pi)
(-56.99288915010725, --------------------------------------------)
pi 0.0107531920731585*sin(0.497820981740837*pi)
(92.99564196348167, --------------------------------------------)
pi 0.0204116090981691*sin(0.495863975998319*pi)
(48.99172795199664, --------------------------------------------)
pi 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:
Minima of the function at points:
$$x_{1} = -86.9953413884714$$
$$x_{2} = 86.9953413884714$$
$$x_{3} = -46.9913758655731$$
$$x_{4} = 30.9869226211336$$
$$x_{5} = -102.996065096535$$
$$x_{6} = -90.9955461762757$$
$$x_{7} = -146.997242926516$$
$$x_{8} = 34.9884178810314$$
$$x_{9} = 90.9955461762757$$
$$x_{10} = 58.9931302339508$$
$$x_{11} = 98.9959061019405$$
$$x_{12} = 130.996906174689$$
$$x_{13} = -22.9823699155424$$
$$x_{14} = 42.9905733959369$$
$$x_{15} = 78.994869591368$$
$$x_{16} = 74.9945959439502$$
$$x_{17} = 54.9926305283549$$
$$x_{18} = 6.94177944869404$$
$$x_{19} = -2.86059330624841$$
$$x_{20} = -370.998907586172$$
$$x_{21} = 2.86059330624841$$
$$x_{22} = -690.999413480515$$
$$x_{23} = 62.993566470984$$
$$x_{24} = -70.9942914583172$$
$$x_{25} = 38.9896062370735$$
$$x_{26} = -82.9951168598645$$
$$x_{27} = 102.996065096535$$
$$x_{28} = 26.9849838868809$$
$$x_{29} = 94.995733717172$$
$$x_{30} = 66.9939506099815$$
$$x_{31} = 46.9913758655731$$
$$x_{32} = -74.9945959439502$$
$$x_{33} = 50.9920524148283$$
$$x_{34} = 70.9942914583172$$
$$x_{35} = 10.9630733012144$$
$$x_{36} = -10.9630733012144$$
$$x_{37} = 82.9951168598645$$
$$x_{38} = -238.998304239951$$
$$x_{39} = -118.996594180944$$
$$x_{40} = -62.993566470984$$
Maxima of the function at points:
$$x_{40} = 32.9877155958269$$
$$x_{40} = 36.9890441958502$$
$$x_{40} = 68.994125974822$$
$$x_{40} = -76.9947363220078$$
$$x_{40} = 56.9928891501073$$
$$x_{40} = 64.9937644514483$$
$$x_{40} = 80.9949962786911$$
$$x_{40} = 44.9909924705645$$
$$x_{40} = 40.9901134171449$$
$$x_{40} = 728.999444053579$$
$$x_{40} = 240.99831831278$$
$$x_{40} = 8.95481716686503$$
$$x_{40} = 96.995821686872$$
$$x_{40} = -112.996413333534$$
$$x_{40} = -8.95481716686503$$
$$x_{40} = 12.9687742527727$$
$$x_{40} = -1000.99959512004$$
$$x_{40} = -32.9877155958269$$
$$x_{40} = -168.997601842789$$
$$x_{40} = -104.996140050787$$
$$x_{40} = 4.91804806591352$$
$$x_{40} = -2596.99984394118$$
$$x_{40} = 1940.99979119796$$
$$x_{40} = -12.9687742527727$$
$$x_{40} = -48.9917279519966$$
$$x_{40} = 76.9947363220078$$
$$x_{40} = 100.995987173567$$
$$x_{40} = -64.9937644514483$$
$$x_{40} = 72.9944478728046$$
$$x_{40} = 52.9923523825456$$
$$x_{40} = 28.986020171625$$
$$x_{40} = 84.9952317659775$$
$$x_{40} = -100.995987173567$$
$$x_{40} = -496.999184536865$$
$$x_{40} = 60.9933555054535$$
$$x_{40} = -80.9949962786911$$
$$x_{40} = -4.91804806591352$$
$$x_{40} = 88.9954460835957$$
$$x_{40} = 24.9837815964593$$
$$x_{40} = -40.9901134171449$$
$$x_{40} = -72.9944478728046$$
$$x_{40} = -56.9928891501073$$
$$x_{40} = 92.9956419634817$$
$$x_{40} = 48.9917279519966$$
Decreasing at intervals
$$\left[130.996906174689, \infty\right)$$
Increasing at intervals
$$\left(-\infty, -690.999413480515\right]$$