У меня есть следующие данные:
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479117.625000000 -100.292800903
479117.687500000 -100.772460937
479117.750000000 -101.344261169
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479119.500000000 -103.382720947
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479119.687500000 -98.745864868
479119.750000000 -99.653961182
479119.812500000 -100.032035828
479119.875000000 -99.955345154
479119.937500000 -99.842536926
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479120.437500000 -102.729179382
479120.500000000 -102.752014160
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479124.687500000 -103.435829163
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479124.812500000 -102.186767578
479124.875000000 -101.180900574
479124.937500000 -101.686195374
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479125.125000000 -103.367576599
479125.187500000 -103.127212524
479125.250000000 -103.924591064
479125.312500000 -103.187667847
479125.375000000 -102.220222473
479125.437500000 -102.674034119
479125.500000000 -101.717445374
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479125.625000000 -100.964996338
479125.687500000 -102.864616394
479125.750000000 -102.009140015
479125.812500000 -99.761398315
479125.875000000 -99.798591614
479125.937500000 -101.713653564
479126.000000000 -103.273422241
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479126.125000000 -101.682983398
479126.187500000 -101.853103638
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479126.312500000 -104.359184265
479126.375000000 -105.037651062
479126.437500000 -104.446434021
479126.500000000 -103.674736023
479126.562500000 -103.374031067
479126.625000000 -102.921363831
479126.687500000 -103.374008179
479126.750000000 -104.299362183
479126.812500000 -104.015937805
479126.875000000 -103.758834839
479126.937500000 -103.698440552
479127.000000000 -103.501396179
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479127.125000000 -101.010841370
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479127.437500000 -104.207763672
479127.500000000 -103.822082520
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479128.187500000 -106.049240112
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479128.375000000 -104.720268250
479128.437500000 -105.791313171
479128.500000000 -106.022468567
479128.562500000 -103.848289490
479128.625000000 -103.887428284
479128.687500000 -104.258583069
479128.750000000 -105.152420044
479128.812500000 -107.673591614
479128.875000000 -107.705734253
479128.937500000 -105.925376892
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479129.062500000 -106.021476746
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479129.187500000 -108.693489075
479129.250000000 -108.675323486
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479129.375000000 -110.940391541
479129.437500000 -109.279312134
479129.500000000 -108.321495056
479129.562500000 -107.995155334
479129.625000000 -109.164222717
479129.687500000 -111.977653503
479129.750000000 -113.194961548
479129.812500000 -114.239585876
479129.875000000 -115.780212402
479129.937500000 -116.979713440
479130.000000000 -117.042602539
479130.062500000 -116.658126831
479130.125000000 -116.624031067
479130.187500000 -116.923446655
479130.250000000 -118.727882385
479130.312500000 -120.354904175
479130.375000000 -121.513587952
479130.437500000 -121.322601318
479130.500000000 -121.338325500
479130.562500000 -120.500923157
479130.625000000 -116.656593323
479130.687500000 -113.295486450
479130.750000000 -111.713729858
479130.812500000 -111.394592285
479130.875000000 -109.731071472
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479131.187500000 -106.258293152
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479131.312500000 -106.613525391
479131.375000000 -105.910820007
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479131.562500000 -101.502128601
479131.625000000 -103.445144653
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479131.812500000 -102.992294312
479131.875000000 -100.679176331
479131.937500000 -99.553001404
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479132.062500000 -102.480346680
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479132.312500000 -100.193199158
479132.375000000 -98.483375549
479132.437500000 -98.084083557
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479132.625000000 -102.540054321
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479132.812500000 -100.926239014
479132.875000000 -100.933807373
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479133.000000000 -100.544723511
479133.062500000 -99.536102295
479133.125000000 -99.533355713
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479133.312500000 -100.118461609
479133.375000000 -101.425323486
479133.437500000 -102.523521423
479133.500000000 -102.540794373
479133.562500000 -101.491882324
479133.625000000 -100.919067383
479133.687500000 -100.623329163
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479133.812500000 -99.252487183
479133.875000000 -101.166763306
479133.937500000 -102.311378479
479134.000000000 -101.306701660
479134.062500000 -100.665534973
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479134.375000000 -101.028564453
479134.437500000 -101.089591980
479134.500000000 -100.819961548
479134.562500000 -100.899681091
479134.625000000 -102.236335754
479134.687500000 -101.911392212
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479134.812500000 -102.417984009
479134.875000000 -101.647750854
479134.937500000 -100.494926453
479135.000000000 -99.920089722
479135.062500000 -101.046142578
479135.125000000 -102.893470764
479135.187500000 -102.895072937
479135.250000000 -103.607261658
479135.312500000 -104.568321228
479135.375000000 -104.253341675
479135.437500000 -102.952842712
479135.500000000 -101.928634644
479135.562500000 -101.746994019
479135.625000000 -102.218338013
479135.687500000 -102.627662659
479135.750000000 -102.185234070
479135.812500000 -103.266464233
479135.875000000 -104.480552673
479135.937500000 -102.991035461
479136.000000000 -101.333572388
479136.062500000 -102.019165039
479136.125000000 -100.434211731
479136.187500000 -99.072113037
479136.250000000 -100.616592407
479136.312500000 -101.648803711
479136.375000000 -102.449073792
479136.437500000 -103.141990662
479136.500000000 -101.611976624
479136.562500000 -101.742187500
479136.625000000 -102.974266052
479136.687500000 -101.894943237
479136.750000000 -101.637077332
479136.812500000 -101.545288086
479136.875000000 -101.042068481
479136.937500000 -101.836784363
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479137.250000000 -98.859046936
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479139.500000000 -103.199569702
479139.562500000 -104.447860718
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479139.687500000 -105.357246399
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479139.812500000 -104.329673767
479139.875000000 -104.890480042
479139.937500000 -103.739471436
479140.000000000 -102.343170166
479140.062500000 -102.630371094
479140.125000000 -103.861930847
479140.187500000 -102.614120483
479140.250000000 -102.544586182
479140.312500000 -103.947563171
479140.375000000 -104.194770813
479140.437500000 -103.187141418
479140.500000000 -102.442695618
479140.562500000 -103.064849854
479140.625000000 -104.047111511
479140.687500000 -103.641082764
479140.750000000 -104.192665100
479140.812500000 -105.001426697
479140.875000000 -106.180221558
479140.937500000 -106.504646301
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479141.062500000 -104.167114258
479141.125000000 -102.925132751
479141.187500000 -102.731872559
479141.250000000 -104.101806641
479141.312500000 -104.532470703
479141.375000000 -103.677726746
479141.437500000 -103.467483521
479141.500000000 -104.314605713
479141.562500000 -106.088348389
479141.625000000 -105.849678040
479141.687500000 -104.784294128
479141.750000000 -104.685859680
479141.812500000 -102.816184998
479141.875000000 -103.009178162
479141.937500000 -105.581695557
479142.000000000 -104.964607239
479142.062500000 -103.978279114
479142.125000000 -104.709609985
479142.187500000 -105.373786926
479142.250000000 -105.477348328
479142.312500000 -107.076698303
479142.375000000 -108.599830627
479142.437500000 -107.518699646
, к которым я хочу соответствовать функции 
В то время как формула является своего рода зверя, оно имеет физический смысл, поэтому я бы не хотел его менять. У меня есть следующий код:
index_min <- which(mydf[,2] == min(mydf[,2]))[1]
n0start <- -119
n1start <- 16
df0start <- 120
df1start <- 1
f0start <- mydf[index_min,1]
f1start <- mydf[index_min,1]
plot(x=mydf[,1],y=mydf[,2])
eq = function(f,n0, n1, f0, f1, df0, df1){ n0+n1*4*(f-f1)^2/(4*(f-f1)^2+(4*((f-f0)/df0)*(f-f1)-df1)^2)}
lines(mydf[,1], eq(mydf[,1],n0start, n1start, f0start, f1start, df0start, df1start), col="red" )
res <- try(nlsLM( y ~ n0+n1*4*(f-f1)^2/(4*(f-f1)^2+(4*((f-f0)/df0)*(f-f1)-df1)^2),
start=c(n0=n0start, n1=n1start,f0=f0start,df0=df0start,f1=f1start,df1=df1start) , data = mydf))
coef(res)
Как видите, начальные значения выглядят довольно прилично, но я получаю ошибку "матрица сингулярного градиента при начальных оценках параметров". Я просмотрел все остальные посты, однако не понимаю, почему моя формула переопределена или почему начальные значения должны быть плохими. 