—————————————————-PARTE 1 DEL EJERCICIO—————————————————————————

————————————————– PUNTO 1: SOMULAR LA TRM——————————————————————–

# Preparar entorno
options(scipen = 999)
set.seed(123456)

# Parámetros de la simulación (mensuales)
s0    <- 3921.58         # valor inicial TRM
mu    <- 0.002342942     # retorno medio mensual
sigma <-  0.029596084    # desviación estándar mensual
N     <- 500             # número de trayectorias
T     <- 72              # meses (6 años)
vec = rep (s0 , N)
mb = matrix ( ncol =N , nrow =T )
mb [1 ,]= vec
k= seq (s0 -30 , s0 +30 ,1)
length (k )
## [1] 61
for (i in 1: N) {
  for (t in 2: T) {
    mb [t,i ]= mb [(t -1) ,i]* exp (( mu -(0.5 *( sigma ^2) ))*(1/ 360) +
                                      sigma *(1/ (360) ^(1 /2) )* qnorm ( runif (1 , min = 0, max = 1) ))
  }
}
matplot (mb , type ="l")

q1 = quantile ( mb [T ,] , 0.975)
q2 = quantile ( mb [T ,] , 0.025)
plot ( density ( mb [T ,]) , ylab ="", xlab ="",
       main =" Empirical ␣ distribution ", lwd = 3)
abline (h = NULL , v =q1 , col = " blue ", lwd = 2)
abline (h = NULL , v =q2 , col = " green ", lwd = 2)

——————————————————– PUNTO 2: CREDITO EN USD Y AMORTIZACION —————————————————-

# Parámetros del crédito
credito_cop <- 300000000          # Valor total en COP
pago_inicial <- 0.10              # 10% pago inicial
s0 <- 3921.58                     # TRM hoy
credito_usd <- (credito_cop * (1 - pago_inicial)) / s0   # Monto financiado en USD

tasa_mensual <- 0.0044            # 0.44% efectiva mensual
n <- 72                           # Plazo en meses

# Cuota fija en USD con sistema francés
cuota_usd <- credito_usd * (tasa_mensual * (1 + tasa_mensual)^n) / ((1 + tasa_mensual)^n - 1)

# Tabla de amortización
saldo <- credito_usd
tabla <- data.frame(
  Mes = integer(),
  Saldo = numeric(),
  Interes = numeric(),
  Cuota = numeric(),
  Amortizacion = numeric()
)

for (t in 1:n) {
  interes <- saldo * tasa_mensual
  amortizacion <- cuota_usd - interes
  saldo <- saldo - amortizacion
  tabla <- rbind(
    tabla,
    data.frame(
      Mes = t,
      Saldo = ifelse(saldo < 0, 0, saldo + amortizacion),  # Saldo al inicio del período
      Interes = interes,
      Cuota = cuota_usd,
      Amortizacion = amortizacion
    )
  )
}

# Mostrar tabla en R
print(tabla)
##    Mes     Saldo    Interes    Cuota Amortizacion
## 1    1 68849.800 302.939121 1117.786     814.8467
## 2    2 68034.954 299.353796 1117.786     818.4320
## 3    3 67216.522 295.752695 1117.786     822.0331
## 4    4 66394.489 292.135750 1117.786     825.6500
## 5    5 65568.839 288.502890 1117.786     829.2829
## 6    6 64739.556 284.854045 1117.786     832.9317
## 7    7 63906.624 281.189145 1117.786     836.5966
## 8    8 63070.027 277.508120 1117.786     840.2777
## 9    9 62229.750 273.810898 1117.786     843.9749
## 10  10 61385.775 270.097409 1117.786     847.6884
## 11  11 60538.086 266.367580 1117.786     851.4182
## 12  12 59686.668 262.621340 1117.786     855.1644
## 13  13 58831.504 258.858616 1117.786     858.9272
## 14  14 57972.577 255.079337 1117.786     862.7064
## 15  15 57109.870 251.283428 1117.786     866.5024
## 16  16 56243.368 247.470818 1117.786     870.3150
## 17  17 55373.053 243.641432 1117.786     874.1444
## 18  18 54498.908 239.795197 1117.786     877.9906
## 19  19 53620.918 235.932039 1117.786     881.8537
## 20  20 52739.064 232.051882 1117.786     885.7339
## 21  21 51853.330 228.154653 1117.786     889.6311
## 22  22 50963.699 224.240276 1117.786     893.5455
## 23  23 50070.154 220.308676 1117.786     897.4771
## 24  24 49172.676 216.359776 1117.786     901.4260
## 25  25 48271.250 212.393502 1117.786     905.3923
## 26  26 47365.858 208.409776 1117.786     909.3760
## 27  27 46456.482 204.408522 1117.786     913.3773
## 28  28 45543.105 200.389662 1117.786     917.3961
## 29  29 44625.709 196.353119 1117.786     921.4327
## 30  30 43704.276 192.298815 1117.786     925.4870
## 31  31 42778.789 188.226672 1117.786     929.5591
## 32  32 41849.230 184.136612 1117.786     933.6492
## 33  33 40915.581 180.028556 1117.786     937.7572
## 34  34 39977.824 175.902424 1117.786     941.8834
## 35  35 39035.940 171.758137 1117.786     946.0276
## 36  36 38089.913 167.595616 1117.786     950.1902
## 37  37 37139.722 163.414779 1117.786     954.3710
## 38  38 36185.351 159.215546 1117.786     958.5702
## 39  39 35226.781 154.997837 1117.786     962.7879
## 40  40 34263.993 150.761570 1117.786     967.0242
## 41  41 33296.969 146.506664 1117.786     971.2791
## 42  42 32325.690 142.233036 1117.786     975.5527
## 43  43 31350.137 137.940604 1117.786     979.8452
## 44  44 30370.292 133.629285 1117.786     984.1565
## 45  45 29386.136 129.298996 1117.786     988.4868
## 46  46 28397.649 124.949654 1117.786     992.8361
## 47  47 27404.813 120.581175 1117.786     997.2046
## 48  48 26407.608 116.193475 1117.786    1001.5923
## 49  49 25406.016 111.786469 1117.786    1005.9993
## 50  50 24400.016 107.360072 1117.786    1010.4257
## 51  51 23389.591 102.914199 1117.786    1014.8716
## 52  52 22374.719  98.448764 1117.786    1019.3370
## 53  53 21355.382  93.963681 1117.786    1023.8221
## 54  54 20331.560  89.458864 1117.786    1028.3269
## 55  55 19303.233  84.934225 1117.786    1032.8516
## 56  56 18270.381  80.389678 1117.786    1037.3961
## 57  57 17232.985  75.825136 1117.786    1041.9606
## 58  58 16191.025  71.240509 1117.786    1046.5453
## 59  59 15144.479  66.635710 1117.786    1051.1501
## 60  60 14093.329  62.010649 1117.786    1055.7751
## 61  61 13037.554  57.365239 1117.786    1060.4205
## 62  62 11977.134  52.699388 1117.786    1065.0864
## 63  63 10912.047  48.013008 1117.786    1069.7728
## 64  64  9842.275  43.306008 1117.786    1074.4798
## 65  65  8767.795  38.578297 1117.786    1079.2075
## 66  66  7688.587  33.829784 1117.786    1083.9560
## 67  67  6604.631  29.060378 1117.786    1088.7254
## 68  68  5515.906  24.269986 1117.786    1093.5158
## 69  69  4422.390  19.458516 1117.786    1098.3273
## 70  70  3324.063  14.625876 1117.786    1103.1599
## 71  71  2220.903   9.771973 1117.786    1108.0138
## 72  72     0.000   4.896712 1117.786    1112.8891

————————————— PUNTO 3: SELECCION DE TRAYECTORIAS Y AMORTIZACION (LARGO, MEDIO,CORTO)————————————

Tomamos el valor final de cada trayectoria

finales <- mb[nrow(mb), ]

# Identificar las trayectorias
idx_larga <- which.max(finales)   # TRM más alta al final (devaluación más fuerte)
idx_corta <- which.min(finales)   # TRM más baja al final (apreciación del COP)
idx_media <- order(finales)[length(finales) %/% 2]  # TRM intermedia

# Extraer las trayectorias
trm_larga <- mb[, idx_larga]
trm_corta <- mb[, idx_corta]
trm_media <- mb[, idx_media]

# --- Función para convertir tabla en USD a COP ---
convertir_a_cop <- function(trm, tabla_usd) {
  data.frame(
    Saldo        = tabla_usd$Saldo * trm,
    Interes      = tabla_usd$Interes * trm,
    Cuota        = tabla_usd$Cuota * trm,
    Amortizacion = tabla_usd$Amortizacion * trm
  )
}
#LARGO
tabla_cop_larga <- convertir_a_cop(trm_larga, tabla)
head(tabla_cop_larga, 72)
##        Saldo    Interes   Cuota Amortizacion
## 1  270000000 1188000.00 4383486      3195486
## 2  267251332 1175905.86 4390827      3214922
## 3  263799630 1160718.37 4386890      3226171
## 4  260478229 1146104.21 4385287      3239182
## 5  257295299 1132099.31 4386246      3254146
## 6  254314321 1118983.01 4390962      3271979
## 7  251925409 1108471.80 4406408      3297936
## 8  248575256 1093731.13 4405482      3311751
## 9  245492652 1080167.67 4409598      3329431
## 10 242478636 1066906.00 4415342      3348436
## 11 239399794 1053359.09 4420320      3366960
## 12 236269891 1039587.52 4424759      3385172
## 13 233800347 1028721.53 4442156      3413434
## 14 230716911 1015154.41 4448519      3433364
## 15 227061982  999072.72 4444182      3445109
## 16 223774684  984608.61 4447318      3462710
## 17 220511102  970248.85 4451338      3481089
## 18 217064474  955083.69 4452045      3496961
## 19 213555907  939645.99 4451803      3512157
## 20 209670975  922552.29 4443902      3521350
## 21 206243101  907469.65 4445917      3538447
## 22 203112309  893694.16 4454858      3561164
## 23 199943996  879753.58 4463628      3583875
## 24 195873105  861841.66 4452558      3590716
## 25 192365622  846408.74 4454485      3608076
## 26 188701660  830287.31 4453166      3622879
## 27 185213605  814939.86 4456410      3641470
## 28 182513059  803057.46 4479504      3676446
## 29 178616247  785911.49 4473984      3688072
## 30 174771186  768993.22 4469969      3700976
## 31 171143558  753031.66 4471885      3718854
## 32 167687339  737824.29 4478900      3741076
## 33 164160142  722304.62 4484743      3762439
## 34 160244227  705074.60 4480452      3775377
## 35 156551071  688824.71 4482806      3793982
## 36 152406666  670589.33 4472523      3801934
## 37 149084280  655970.83 4486956      3830985
## 38 145140120  638616.53 4483460      3844843
## 39 141514546  622664.00 4490417      3867753
## 40 137775326  606211.44 4494610      3888399
## 41 134009447  589641.57 4498723      3909082
## 42 130604315  574658.99 4516149      3941490
## 43 126364203  556002.49 4505502      3949500
## 44 122725137  539990.60 4516928      3976937
## 45 119007836  523634.48 4526804      4003169
## 46 115346359  507523.98 4540253      4032729
## 47 111294965  489697.85 4539492      4049794
## 48 107221726  471775.59 4538500      4066724
## 49 103483154  455325.88 4552937      4097611
## 50  99350567  437142.49 4551335      4114193
## 51  95193073  418849.52 4549266      4130416
## 52  91064547  400684.01 4549360      4148676
## 53  86944739  382556.85 4550871      4168314
## 54  82834398  364471.35 4554058      4189587
## 55  78763430  346559.09 4560927      4214368
## 56  74512667  327855.73 4558701      4230845
## 57  70510274  310245.20 4573519      4263274
## 58  66358424  291977.07 4581211      4289234
## 59  62067068  273095.10 4581055      4307959
## 60  57813949  254381.38 4585404      4331023
## 61  53520107  235488.47 4588592      4353103
## 62  49239518  216653.88 4595359      4378706
## 63  44897906  197550.79 4599159      4401608
## 64  40519524  178285.91 4601797      4423511
## 65  35983105  158325.66 4587402      4429077
## 66  31603945  139057.36 4594659      4455602
## 67  27244956  119877.81 4611011      4491133
## 68  22718564   99961.68 4603865      4503904
## 69  18261031   80348.54 4615586      4535237
## 70  13705137   60302.60 4608639      4548337
## 71   9165529   40328.33 4613033      4572705
## 72         0   20148.86 4599434      4579286
#TRAYECTORIA MEDIA
tabla_cop_media <- convertir_a_cop(trm_media, tabla)
head(tabla_cop_media, 72)
##        Saldo    Interes   Cuota Amortizacion
## 1  270000000 1188000.00 4383486      3195486
## 2  266851349 1174145.93 4384256      3210110
## 3  263114884 1157705.49 4375503      3217797
## 4  259728899 1142807.16 4372671      3229864
## 5  256390933 1128120.11 4370828      3242708
## 6  253559598 1115662.23 4377931      3262269
## 7  250817423 1103596.66 4387028      3283431
## 8  247727612 1090001.49 4390460      3300458
## 9  244481554 1075718.84 4391437      3315718
## 10 241538577 1062769.74 4398224      3335454
## 11 237833785 1046468.65 4391404      3344936
## 12 234732517 1032823.07 4395968      3363145
## 13 231131886 1016980.30 4391456      3374475
## 14 227619138 1001524.21 4388790      3387265
## 15 224131210  986177.33 4386819      3400642
## 16 220498760  970194.55 4382212      3412018
## 17 217194991  955657.96 4384397      3428740
## 18 213422178  939057.58 4377340      3438283
## 19 209970843  923871.71 4377068      3453197
## 20 206870723  910231.18 4384552      3474321
## 21 204077657  897941.69 4399237      3501296
## 22 200585744  882577.28 4399443      3516866
## 23 196941524  866542.71 4396600      3530057
## 24 193721144  852373.04 4403640      3551266
## 25 190137926  836606.87 4402900      3566293
## 26 186763402  821758.97 4407425      3585666
## 27 183192385  806046.49 4407778      3601731
## 28 179678684  790586.21 4409938      3619352
## 29 175795206  773498.91 4403322      3629823
## 30 171894545  756336.00 4396395      3640059
## 31 168181541  739998.78 4394489      3654491
## 32 164291454  722882.40 4388197      3665314
## 33 160502672  706211.76 4384824      3678612
## 34 156688674  689430.17 4381038      3691608
## 35 152800936  672324.12 4375422      3703098
## 36 149049065  655815.89 4373991      3718175
## 37 145101688  638447.43 4367093      3728645
## 38 141335372  621875.64 4365929      3744053
## 39 137781652  606239.27 4371968      3765729
## 40 134467629  591657.57 4386704      3795047
## 41 130789779  575475.03 4390639      3815164
## 42 127169889  559547.51 4397391      3837843
## 43 123161457  541910.41 4391309      3849398
## 44 119235774  524637.41 4388501      3863863
## 45 115321509  507414.64 4386584      3879169
## 46 111298758  489714.54 4380932      3891218
## 47 107409334  472601.07 4381005      3908404
## 48 103512719  455455.96 4381504      3926048
## 49  99622490  438338.96 4383080      3944741
## 50  95858101  421775.65 4391342      3969567
## 51  92043633  404991.99 4398754      3993762
## 52  88132930  387784.89 4402904      4015119
## 53  84273957  370805.41 4411077      4040271
## 54  80279456  353229.61 4413593      4060364
## 55  76347720  335929.97 4421042      4085112
## 56  72164444  317523.55 4415036      4097512
## 57  68134854  299793.36 4419442      4119648
## 58  63852352  280950.35 4408199      4127248
## 59  59672759  262560.14 4404335      4141775
## 60  55451546  243986.80 4398035      4154048
## 61  51394031  226133.73 4406311      4180177
## 62  47150934  207464.11 4400439      4192975
## 63  42939401  188933.36 4398538      4209604
## 64  38674419  170167.44 4392248      4222081
## 65  34460217  151624.95 4393253      4241628
## 66  30248330  133092.65 4397577      4264484
## 67  25936846  114122.12 4389623      4275500
## 68  21653287   95274.46 4387989      4292715
## 69  17350737   76343.24 4385503      4309160
## 70  13047155   57407.48 4387379      4329972
## 71   8711101   38328.85 4384318      4345989
## 72         0   19243.62 4392793      4373549
#CORTO
tabla_cop_corta <- convertir_a_cop(trm_corta, tabla)
head(tabla_cop_corta, 72)
##        Saldo    Interes   Cuota Amortizacion
## 1  270000000 1188000.00 4383486      3195486
## 2  267153114 1175473.70 4389214      3213740
## 3  264029940 1161731.73 4390720      3228988
## 4  260853870 1147757.03 4391611      3243854
## 5  256830118 1130052.52 4378315      3248263
## 6  253453728 1115196.41 4376103      3260907
## 7  250215559 1100948.46 4376501      3275552
## 8  246486187 1084539.22 4368458      3283919
## 9  242914183 1068822.40 4363283      3294461
## 10 240005341 1056023.50 4370305      3314282
## 11 236289271 1039672.79 4362886      3323214
## 12 233045772 1025401.40 4364379      3338978
## 13 229789993 1011075.97 4365960      3354884
## 14 225760402  993345.77 4352951      3359605
## 15 222298324  978112.62 4350945      3372832
## 16 219181699  964399.48 4356037      3391637
## 17 215744712  949276.73 4355121      3405845
## 18 212632148  935581.45 4361137      3425555
## 19 208882840  919084.50 4354388      3435303
## 20 205662385  904914.49 4358941      3454027
## 21 202163344  889518.71 4357971      3468452
## 22 199002310  875610.16 4364714      3489103
## 23 195704449  861099.57 4368983      3507883
## 24 191832860  844064.58 4360715      3516651
## 25 188309748  828562.89 4360566      3532003
## 26 184911981  813612.71 4363734      3550121
## 27 181015516  796468.27 4355400      3558932
## 28 177589036  781391.76 4358651      3577259
## 29 173958394  765416.93 4357314      3591897
## 30 170560616  750466.71 4362279      3611812
## 31 167136597  735401.03 4367186      3631785
## 32 163236611  718241.09 4360022      3641781
## 33 159235302  700635.33 4350200      3649565
## 34 155299908  683319.59 4342208      3658888
## 35 151643912  667233.21 4342291      3675058
## 36 147844094  650514.01 4338630      3688116
## 37 143997421  633588.65 4333858      3700269
## 38 139946197  615763.27 4323016      3707253
## 39 136048630  598613.97 4316978      3718364
## 40 131905669  580384.94 4303126      3722741
## 41 128177736  563982.04 4302952      3738970
## 42 124534013  547949.66 4306245      3758296
## 43 120788455  531469.20 4306699      3775230
## 44 116866145  514211.04 4301286      3787075
## 45 112912329  496814.25 4294944      3798129
## 46 109060230  479865.01 4292819      3812954
## 47 105398206  463752.10 4298975      3835223
## 48 101584487  446971.74 4299886      3852914
## 49  97680393  429793.73 4297634      3867840
## 50  93931227  413297.40 4303070      3889773
## 51  90016477  396072.50 4301877      3905804
## 52  86244764  379476.96 4308576      3929099
## 53  82093949  361213.37 4296971      3935757
## 54  77906655  342789.28 4283142      3940352
## 55  73928744  325286.47 4280967      3955680
## 56  69856730  307369.61 4273849      3966480
## 57  65888842  289910.91 4273758      3983847
## 58  61836631  272081.18 4269038      3996957
## 59  57767379  254176.47 4263703      4009526
## 60  53701801  236287.92 4259257      4022969
## 61  49576166  218135.13 4250455      4032320
## 62  45572280  200518.03 4253108      4052590
## 63  41480220  182512.97 4249065      4066552
## 64  37429365  164689.21 4250848      4086159
## 65  33386148  146899.05 4256322      4109423
## 66  29250704  128703.10 4252540      4123836
## 67  25077343  110340.31 4244158      4133818
## 68  20939496   92133.78 4243341      4151207
## 69  16742158   73665.49 4231681      4158016
## 70  12581772   55359.80 4230884      4175525
## 71   8384934   36893.71 4220158      4183264
## 72         0   18454.70 4212705      4194250

——————————————————– PARTE 2 DEL EJERCICIO ——————————————————————–

# Preparar entorno
options(scipen = 999)
set.seed(123456)

# Parámetros de la simulación (mensuales)
s0    <- 3947       # valor inicial del futuro
mu    <- -0.0164     # retorno medio mensual
sigma <- 0.0299      # desviación estándar mensual
N     <- 500         # número de trayectorias
T     <- 72          # meses totales (6 años)
# Inicializar matriz de simulación
vec <- rep(s0, N)
mb  <- matrix(ncol = N, nrow = T)
mb[1, ] <- vec

# Simulación de trayectorias BMG mensual
for (i in 1:N) {
  for (t in 2:T) {
    mb[t, i] <- mb[t - 1, i] * exp((mu - 0.5 * sigma^2) * 1 +
                                     sigma * sqrt(1) * rnorm(1))
  }
}
# Extraer solo meses 37 a 72
mb_sub <- mb[37:72, ]
# Calcular estadísticas por mes
p10   <- apply(mb_sub, 1, quantile, probs = 0.10)
p50   <- apply(mb_sub, 1, quantile, probs = 0.50)  # mediana
p90   <- apply(mb_sub, 1, quantile, probs = 0.90)
media <- apply(mb_sub, 1, mean)

# Crear data frame con resultados
df_futuro <- data.frame(
  Mes_Absoluto = 37:72,                # mes dentro de los 72 totales
  Mes_Relativo = 1:36,                 # mes relativo al subperiodo
  P10   = round(p10, 4),
  Mediana = round(p50, 4),
  P90   = round(p90, 4),
  Media = round(media, 4)
)

# Mostrar en consola
print(df_futuro)
##    Mes_Absoluto Mes_Relativo       P10  Mediana      P90    Media
## 1            37            1 1713.0104 2149.611 2694.320 2193.630
## 2            38            2 1701.7978 2115.530 2653.144 2155.130
## 3            39            3 1665.0674 2091.999 2611.980 2122.961
## 4            40            4 1643.7221 2048.261 2560.121 2088.601
## 5            41            5 1601.2367 2012.643 2527.900 2051.460
## 6            42            6 1572.2060 1987.525 2490.902 2017.311
## 7            43            7 1528.2808 1950.280 2468.732 1986.596
## 8            44            8 1504.7385 1919.655 2435.794 1956.418
## 9            45            9 1478.3354 1883.180 2400.878 1926.094
## 10           46           10 1447.5499 1853.451 2356.118 1894.191
## 11           47           11 1439.3974 1823.874 2354.773 1869.268
## 12           48           12 1412.7454 1804.890 2300.280 1838.158
## 13           49           13 1381.1684 1781.006 2270.780 1807.731
## 14           50           14 1372.6939 1742.849 2243.545 1777.219
## 15           51           15 1349.2013 1717.696 2203.971 1750.737
## 16           52           16 1310.3206 1694.187 2161.612 1723.055
## 17           53           17 1279.3292 1658.189 2156.208 1692.616
## 18           54           18 1276.6049 1624.605 2129.355 1662.417
## 19           55           19 1233.7669 1597.217 2072.175 1632.530
## 20           56           20 1222.4493 1576.264 2037.046 1607.023
## 21           57           21 1192.9219 1538.385 2011.790 1579.512
## 22           58           22 1177.0851 1519.358 1967.555 1555.172
## 23           59           23 1147.3320 1496.895 1964.018 1533.631
## 24           60           24 1123.7747 1485.367 1953.510 1514.528
## 25           61           25 1107.2298 1459.795 1899.001 1490.780
## 26           62           26 1090.7268 1439.811 1875.004 1466.384
## 27           63           27 1058.6761 1411.117 1853.424 1443.005
## 28           64           28 1045.1061 1380.151 1826.215 1418.481
## 29           65           29 1023.5776 1349.435 1804.840 1391.239
## 30           66           30 1009.3553 1339.998 1771.937 1366.049
## 31           67           31  966.2454 1317.225 1749.744 1344.875
## 32           68           32  964.3829 1308.927 1713.828 1323.852
## 33           69           33  938.4152 1279.552 1691.992 1301.067
## 34           70           34  936.7451 1245.144 1692.642 1282.031
## 35           71           35  903.1901 1221.802 1664.304 1258.386
## 36           72           36  892.9537 1208.017 1634.454 1237.969
# Si usas RStudio, esto abre la tabla en el visor
View(df_futuro)
# Supongamos que ya tienes la matriz mb con 72 meses simulados x N trayectorias

# Seleccionemos una trayectoria de ejemplo (por ejemplo la primera)
trayectoria <- mb[37:72, 1]  # meses 37 a 72

# Definir parámetros del contrato
tam_contrato <- 50000          # USD por contrato
margen_inicial_pct <- 0.063    # 6.3% garantía inicial según BVC
margen_mantenimiento_pct <- 0.75  # asumimos 75% del inicial

# Construir el data frame con los meses 37 a 72
df_expo <- data.frame(
  Mes = 37:72,
  TRM = trayectoria,
  Exposicion = trayectoria * tam_contrato,
  Margen_Inicial = trayectoria * tam_contrato * margen_inicial_pct,
  Margen_Mantenimiento = trayectoria * tam_contrato * margen_inicial_pct * margen_mantenimiento_pct
)

# Mostrar primeras filas
head(df_expo, 10)
##    Mes      TRM Exposicion Margen_Inicial Margen_Mantenimiento
## 1   37 2555.293  127764674        8049174              6036881
## 2   38 2632.585  131629255        8292643              6219482
## 3   39 2668.377  133418850        8405388              6304041
## 4   40 2706.994  135349708        8527032              6395274
## 5   41 2574.425  128721260        8109439              6082080
## 6   42 2451.616  122580785        7722589              5791942
## 7   43 2481.438  124071886        7816529              5862397
## 8   44 2452.493  122624641        7725352              5794014
## 9   45 2347.756  117387814        7395432              5546574
## 10  46 2319.487  115974338        7306383              5479787