Generalized Eigenvalue Problem using MATLAB

Question

I'm trying to solve a generalized eigenvalue problem. I have two matrices $H$ and $S$ such that:

$$ HX=λSX $$

I need to find the eigenvalues $\lambda$. The matrices $H$ and $S$ are real, asymmetric, contain positive and negative decimal numbers, and (can be) singular. I am using MATLAB and have tried two different approaches:

I used eig(H,S) command which uses QZ Algorithm to solve for eigenvalues. I formed an equation in $\lambda$ by using $|H-\lambda S|=0$ and then solved for $\lambda$. Here are the matrices: (both $H$ and $S$ are $24\times 24$)

H=[0,0,0,0,192,1917.04064,10332.51505,40092.51227,125681.1486,338350.2206,811892.8294,1779728.921,3625982.355,6953387.916,12670976.81,22100000,37132930.27,60353006.25,95276316.19,146559937.4,220274060.5,324208411.9,468219308,664618721.8;
0,0,0,0,192,1893.475124,10051.90014,38308.22391,117609.6433,309187.9535,722364.2569,1537115.973,3030677.025,5606681.841,9824567.083,16426180.74,26355891.41,40770017.02,61031174.08,88683247.04,125403139.6,172926323.5,232944447.3,306974887;
0,0,0,0,192,1846.924351,9507.779872,34923.83828,102685.9158,256815.0258,566753.8301,1130503.089,2072244.588,3531888.862,5644710.273,8510616.36,12154554.65,16481872.51,21234784.98,25958063.51,29983201.26,32440241.94,32304892.86,28485362.66;
0,0,0,0,192,1778.534558,8732.953666,30281.20319,83090.50097,191433.6927,383369.9941,681577.7806,1089000.57,1571702.814,2043718.6,2360415.659,2327150.205,1728131.214,376286.8361,-1820993.208,-4791939.112,-8243585.409,-11638086.16,-14220529.21;
0,0,0,0,192,1689.989727,7773.203992,24831.36406,61515.88289,124689.9821,212051.9399,303583.89,356337.2627,308129.1939,94242.56924,-323226.8121,-920239.2345,-1583058.32,-2104105.201,-2214813.175,-1659107.74,-295993.1841,1796496.926,4254923.427;
0,0,0,0,192,1583.470126,6683.555129,19072.50505,40639.69537,66711.57632,81796.22718,60590.29663,-21861.2573,-171429.7577,-355062.5907,-492927.1661,-475398.2758,-208930.4549,320950.1747,997476.1882,1566265.895,1699768.472,1129529.762,-194208.6509;
0,0,0,0,192,1461.598622,5523.845413,13484.72812,22648.14037,23924.65349,4088.400074,-44523.67789,-110266.4937,-154796.0153,-124116.6074,18352.09343,250026.0416,467393.1673,513093.6957,258167.4211,-292568.7362,-936296.041,-1313188.428,-1070939.742;
0,0,0,0,192,1327.376095,4354.022806,8472.235861,8915.430969,-1775.330646,-26379.77787,-53287.95266,-55123.02039,-5131.095738,92963.75123,184430.9087,180646.3185,21137.78348,-252747.0452,-475735.34,-436097.8969,-33470.52706,583046.8515,1024123.527;
0,0,0,0,192,1184.107549,3229.595901,4321.651839,-104.2768198,-12455.61648,-25344.84529,-20852.91355,14642.78081,67162.133,88643.95935,29331.92183,-103721.9759,-215885.8219,-175668.2952,63339.97258,366040.1121,463007.7228,161145.8379,-426631.9431;
0,0,0,0,192,1035.320732,2197.653181,1181.837405,-4776.384006,-12614.95411,-10733.55999,10443.54925,39434.88701,40860.0242,-11919.57845,-90391.52336,-109544.5177,-4764.383231,169447.4417,238928.2291,63214.86651,-273067.0285,-452649.3406,-197417.4769;
0,0,0,0,192,884.6792681,1293.804398,-933.634351,-6033.445815,-7367.269353,3768.214436,22179.4179,22745.61092,-13409.71654,-59759.11695,-51183.66478,39553.74618,132447.0485,93359.81585,-98263.14966,-255824.9417,-144286.083,212696.4921,445204.5408;
0,0,0,0,192,735.8924507,540.3053094,-2124.343367,-5057.868211,-969.9812354,11405.43117,15940.52452,-5622.481002,-37623.47011,-29881.32575,35855.80045,87872.36995,28692.89466,-112944.5884,-154561.6584,24454.28757,254280.9736,202369.5839,-178659.2813;
0,0,0,0,192,592.6239049,-54.49033533,-2567.50857,-2988.296704,3941.876267,11526.38431,2233.953421,-22136.82236,-24139.16168,20459.96219,60268.45865,14532.0698,-88098.13253,-93277.95948,64910.42847,192595.8473,49803.13745,-244897.5404,-254777.9707;
0,0,0,0,192,458.4013779,-495.3380524,-2477.176593,-714.5839156,6392.684212,6873.986266,-9352.41825,-21134.06087,3844.754647,42020.47316,20505.10932,-58980.138,-70793.54333,51327.19794,141815.5672,6229.868714,-208390.0472,-130756.2533,224730.6889;
0,0,0,0,192,336.5298736,-798.086388,-2066.223865,1211.650343,6609.005295,832.2069828,-14542.95731,-9394.727768,23888.17206,29260.48864,-28610.53289,-63533.47519,18266.13986,110340.0964,20413.44929,-159630.1792,-99650.79156,191428.6434,224840.2275;
0,0,0,0,192,230.010273,-986.6727322,-1517.645248,2561.671612,5397.538212,-4248.815769,-13851.25499,3944.496017,28647.88724,2246.348802,-50351.46819,-19936.09886,77156.40402,55808.14847,-103790.0999,-116346.81,120768.0917,206007.3722,-114289.9057;
0,0,0,0,192,141.4654422,-1089.461027,-968.7547191,3346.025684,3627.717551,-7474.097775,-9965.085871,13492.9252,22500.21035,-20544.91549,-44251.15549,26525.3978,78409.54708,-27774.42335,-127872.1365,18879.12551,194650.9903,7368.517829,-279197.6607;
0,0,0,0,192,73.07564879,-1135.312342,-508.5655728,3706.949976,1946.428626,-9020.436512,-5497.089494,18315.25514,12841.39554,-32819.98602,-26305.72752,53592.96081,48907.83539,-81344.97478,-84369.59991,116249.2281,137093.641,-157744.2065,-212101.4947;
0,0,0,0,192,26.52487642,-1149.801347,-185.5323873,3822.418606,714.8963246,-9523.125445,-2036.182875,19914.17359,4805.440196,-36987.23947,-9962.723932,63039.66842,18780.08487,-100646.6018,-32907.74918,152629.087,54418.22672,-222018.2854,-85848.08848;
0,0,0,0,192,2.959359616,-1151.972632,-20.71532046,3839.781056,79.90093794,-9599.042127,-227.8620289,20156.93483,538.572741,-37623.95402,-1118.549352,64493.6094,2112.7619,-103642.0699,-3710.543262,158327.7533,6151.495274,-232190.8611,-9731.39151;
1,0,-1,0,1,0,-1,0,1,0,-1,0,1,0,-1,0,1,0,-1,0,1,0,-1,0;
0,0,4,0,-16,0,36,0,-64,0,100,0,-144,0,196,0,-256,0,324,0,-400,0,484,0;
0,0,0,24,192,840,2688,7056,16128,33264,63360,113256,192192,312312,489216,742560,1096704,1581408,2232576,3093048,4213440,5653032,7480704,9775920;
0,1,4,9,16,25,36,49,64,81,100,121,144,169,196,225,256,289,324,361,400,441,484,529]
S=[1,0.998458667,0.993839419,0.986156496,0.975433581,0.96170373,0.945009268,0.925401657,0.902941342,0.87769756,0.84974813,0.819179209,0.786085032,0.750567618,0.712736454,0.672708162,0.630606134,0.586560159,0.540706014,0.493185053,0.444143767,0.393733335,0.342109153,0.289430364;
1,0.98618496,0.945121551,0.877944359,0.786509494,0.673343309,0.541572595,0.394838187,0.237194368,0.07299685,-0.093217576,-0.256856394,-0.413398249,-0.558517877,-0.688205612,-0.798878172,-0.887477663,-0.951556077,-0.98934292,-0.999794139,-0.982620967,-0.938297899,-0.868049586,-0.773816993;
1,0.961939766,0.850656228,0.67462034,0.447232036,0.18580022,-0.089774795,-0.35851611,-0.599967012,-0.795748145,-0.930956556,-0.99530012,-0.983880972,-0.897568346,-0.742932397,-0.531744087,-0.280079168,-0.007094493,0.266430219,0.519674138,0.733360219,0.891222577,0.981244656,0.996573933;
1,0.926320082,0.716137789,0.400425549,0.025706666,-0.352800347,-0.679318759,-0.90573287,-0.998678335,-0.944458724,-0.751063831,-0.446992295,-0.077052048,0.304242576,0.640704064,0.882751506,0.994716832,0.960100849,0.784004562,0.492377492,0.128193756,-0.254880591,-0.600395776,-0.857436738;
1,0.880202983,0.549514582,0.087165765,-0.396067449,-0.784405265,-0.984804259,-0.949250027,-0.686261152,-0.258848199,0.230583238,0.664768308,0.939678856,0.989447956,0.802151229,0.422663852,-0.058091262,-0.524928056,-0.86599522,-0.999575095,-0.89366274,-0.573634124,-0.116166194,0.369134463;
1,0.824724024,0.360339432,-0.230362851,-0.740310987,-0.990741662,-0.893865914,-0.483643725,0.096120716,0.642189852,0.963138082,0.946456378,0.597992543,0.039901255,-0.532177495,-0.917700386,-0.981521616,-0.701268527,-0.175184388,0.412310981,0.85526993,0.998412337,0.79155935,0.307223688;
1,0.761249282,0.15900094,-0.51917058,-0.949437402,-0.926346503,-0.460923818,0.224590651,0.802862762,0.997766752,0.716235686,0.092701052,-0.575098468,-0.968287643,-0.899118079,-0.400618342,0.289177228,0.840890257,0.991076981,0.668023024,0.025987114,-0.62845768,-0.98281303,-0.867873748;
1,0.691341716,-0.044093263,-0.75230874,-0.996111568,-0.624998222,0.131936882,0.807425162,0.984476513,0.553794202,-0.218754445,-0.856262349,-0.965185319,-0.4782834,0.303870785,0.8984405,0.93838801,0.399053054,-0.386623964,-0.933631603,-0.904292986,-0.316719326,0.46637042,0.96156198;
1,0.616722682,-0.239306267,-0.911893888,-0.885465021,-0.180278837,0.663100925,0.998177599,0.568096607,-0.297461473,-0.934999082,-0.855808809,-0.120594327,0.707062296,0.992717038,0.517399932,-0.354532491,-0.954696389,-0.823033344,-0.060470273,0.748446566,0.98363822,0.464817436,-0.410311308;
1,0.539229548,-0.418462989,-0.990524765,-0.649777453,0.289766361,0.96227862,0.74801177,-0.155578523,-0.915796843,-0.832070912,0.0184424,0.851960286,0.90036192,0.119043216,-0.771978681,-0.951590646,-0.254272907,0.677367717,0.984786282,0.384684007,-0.569920316,-0.999319756,-0.507805164;
1,0.460770452,-0.575381181,-0.991007746,-0.337872993,0.679643962,0.964192705,0.208899055,-0.771683681,-0.920037132,-0.07616817,0.849845048,0.859335144,-0.057932562,-0.91272237,-0.783178435,0.190991406,0.959184828,0.692936648,-0.320615363,-0.98839682,-0.590232736,0.444473211,0.99983298;
1,0.383277318,-0.706196995,-0.924615899,-0.002571609,0.92264462,0.70982912,-0.378521817,-0.999986774,-0.38802268,0.702546189,0.926562719,0.007714758,-0.920648935,-0.713442468,0.373756304,0.999947095,0.392757778,-0.698876799,-0.928485029,-0.012857704,0.918628896,0.717036943,-0.368980903;
1,0.308658284,-0.809460128,-0.808351431,0.310451397,0.999998222,0.306864073,-0.810565945,-0.807239861,0.312243405,0.999992888,0.305068772,-0.811668881,-0.80612542,0.314034304,0.999983998,0.303272386,-0.81276893,-0.805008112,0.315824085,0.999971552,0.301474921,-0.813866089,-0.803887941;
1,0.238750718,-0.88599619,-0.66181517,0.569978496,0.93398072,-0.124001362,-0.993191548,-0.350249028,0.825947135,0.74463997,-0.47038048,-0.969247324,0.007563492,0.972858903,0.456978031,-0.754651237,-0.81732508,0.364377338,0.991315782,0.10897737,-0.939278931,-0.557484408,0.673079326;
1,0.175275976,-0.938556665,-0.504288846,0.761777225,0.771331339,-0.491385519,-0.943587492,0.160609082,0.999889319,0.18990407,-0.933318077,-0.517080544,0.752054483,0.78071471,-0.478373418,-0.948409446,0.145906635,0.999557301,0.204490127,-0.927872888,-0.529757779,0.742165265,0.789925261;
1,0.119797017,-0.971297349,-0.352514068,0.886837082,0.564994942,-0.751467664,-0.745042111,0.572960019,0.882319914,-0.361561431,-0.968947876,0.1294073,0.999953093,0.110175495,-0.973555702,-0.343433634,0.891271052,0.556976861,-0.757822719,-0.738546663,0.580871344,0.877719972,-0.370574875;
1,0.073679918,-0.989142539,-0.2194398,0.956805927,0.360434564,-0.903692348,-0.49360252,0.830955162,0.616051936,-0.74017385,-0.725123833,0.633319721,0.818449723,-0.512713105,-0.894003042,0.380972963,0.950143155,-0.240960024,-0.985650985,0.095714657,0.999755481,0.051609146,-0.992150366;
1,0.038060234,-0.997102837,-0.113960168,0.988428136,0.18919978,-0.97402616,-0.263343106,0.95398036,0.335960537,-0.928406887,-0.406631304,0.897453922,0.474945916,-0.861300817,-0.540508536,0.820157054,0.602939275,-0.774261035,-0.661876387,0.723878695,0.716978371,-0.669301966,-0.76792595;
1,0.01381504,-0.999618289,-0.041434573,0.998473449,0.069022474,-0.996566352,-0.096557681,0.993898456,0.124019175,-0.990471796,-0.151385989,0.986288989,0.178637233,-0.981353228,-0.2057521,0.975668281,0.232709893,-0.969238489,-0.259490029,0.962068758,0.286072066,-0.954164565,-0.312435708;
1,0.001541333,-0.999995249,-0.004623985,0.999980994,0.007706592,-0.999957238,-0.010789127,0.999923978,0.013871559,-0.999881217,-0.016953859,0.999828954,0.020035998,-0.999767189,-0.023117946,0.999695925,0.026199675,-0.99961516,-0.029281155,0.999524896,0.032362357,-0.999425133,-0.035443251;
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]

Results from eig(H,S):

          -10.4013941701241 +                     0i
             495.8709816739 +                     0i
          -2075.89359089271 +                     0i
           3810.96559828315 +                     0i
          -12007.5792049748 -      7859.80373595807i
          -12007.5792049748 +      7859.80373595807i
           13744.8803145627 -      6829.57196964173i
           13744.8803145627 +      6829.57196964173i
           40714.6215488508 +                     0i
           161777.282995074 +                     0i
          -222054.135160397 +                     0i
           456554.085296176 +                     0i
           1046529.30310225 +                     0i
           2209556.44199227 +                     0i
          -3698516.26538781 +                     0i
           5938712.03152599 +                     0i
           29139261.3696759 +                     0i
           35187640.9660181 +                     0i
          -106153683.549455 +                     0i
            625134760.07866 +                     0i
                        Inf +                     0i
                        Inf +                     0i
                        Inf +                     0i
                        Inf +                     0i

Results from putting determinant equal to 0:

6.0880681896251522577558901777469
493.13352335963732050050918987025
3805.0426185157246029406709075097
14617.451723278368450735731815741
39943.815388339366263101056654306
89135.406154470667286843490819588
173881.32991449447500370097212608
308208.37416682144561534408214656
508470.65137071189157395633863007
793718.91013854156465411829146852
1184484.6868564064238468530882583
1708985.9187321214627561917325303
2400030.5803698046017748760892131
3509269.6989698602635588940827738
6117137.3935227069102232614222001
11673551.342361595565898213914818
30121894.392585463384868409705274
104001718.25765847906945083161619
953411363.34772056816450115047618
2832353346.2556813059459515513392

The problem is that both of the approaches are giving different eigenvalues. The second method(determinant one) gives correct results as they match with the values present in the research paper that I'm trying to implement. So, I have the following questions:

1. Why is eig(H,S) not giving correct eigenvalues?
2. Evaluating the determinant involves symbolic computation and the size of my matrices could be as large as $100\times100$ and this takes very long for MATLAB to solve. Is there any efficient way to evaluate determinants of large(non-sparse) symbolic matrices?