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TwoDimSD.jl
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TwoDimSD.jl
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module TwoDimSD
using Base: Float64
using LinearAlgebra, Interpolations, Random, QuantEcon, Statistics, DataFrames, Distributions, CSV, Plots, Optim, Roots, SchumakerSpline,NLopt
using DelimitedFiles, NaNMath, JLD
using Parameters: @with_kw, @unpack
export Solve_eq_float2D,simulate_eq_2D, Solve_eq_peg2D, run_2D, unpack_params, TD_assumed, TD_calib, TD_gird, run_2D_calib, run_SMM, wrapper_SMM, run_2D_calib_whole_exp, simulate_eq_2D_default
global β = 0.9
global σ = 2.0
global α = 0.75
global h_bar = 1.0
global a = 0.26
global ζ = 0.5
global y_t = 1.0
global θ = 0.0385
global δ_1 = 0.58 #-0.35
global δ_2 = 2.15# 0.46
global ρ = 0.93
global σ_μ = 0.037
global r =0.01
global n_y = 21
global n_B = 35
global n_d = 15
global B_min = 0.0
global B_max = 1.0
global d_min = 0.0
global d_max = 0.4
global grid_B = B_min:(B_max-B_min)/(n_B-1):B_max
global grid_d = d_min:(d_max-d_min)/(n_d-1):d_max
global w_bar = 0.95* α * (1.0-a)/a
global c_t_min = 1.0
global itp, disc
global k = 0.3
global c_t_min = 1.0
global P_stat, y_t_stat
global pen = 0.03
global ERR_glob = "peg"
@with_kw struct TD_assumed #assumed paramters from TwinD;s paper
σ::Float64 = 2.0 #CRRA param
α::Float64 = 0.75 # production function param
a::Float64 = 0.26 #CES utility of the tradeable good in the CES function of the final good
ζ::Float64 = 0.5 #CES final good parameter
y_t::Float64 = 1.0 # tradeable goods long term expectation
ρ::Float64 = 0.9317 #tradeables shock persitanece (Argentinan economy from TwinD's)
σ_μ::Float64 = 0.037 #tradeables shock variance (Argentinan economy from TwinD's)
r::Float64 = 0.01 #interest rate
θ::Float64 = 1.0 # probability of the reentry to the market after the default
h_bar::Float64 = 1.0 #maximal employment level
end
@with_kw struct TD_calib #values which should be calibrated
β::Float64 = 0.96 #discount factor
δ_1::Float64 = 0.015 #penalty function param for the default (in form δ_1 y_t+ δ_2 y_t^2 )
δ_2::Float64 = 0.6 #penalty function param for the default (in form δ_1 y_t+ δ_2 y_t^2 )
w_bar::Float64 = 0.99* α * (1.0-a)/a #for the peg model calibration, minimal wage
pen::Float64 = 0.025 #percentage of consumption due to
k::Float64 = 0.3
end
@with_kw struct TD_gird #technical params for the asset/income grid structure, discertization, interpolation method
n_y::Int64 = 21 #number of grid points for income, 21 is magical number used in all Arellano papers
n_B::Int64 = 50 #number of grid points for the Schumker splines, about 30 works for cubic splines, for the vfi, fior a good precision at least 200 points
n_d::Int64 = 20
B_min::Float64 = 0.0 #minimal debt level for (works for float)
B_max::Float64 = 1.0 #maximal debt level
d_min = 0.0
d_max = 0.4
end
-
function DiscretizeAR(ρ, var, n, method)
#n:number of states
#\rho , \sigma : values for
@assert n > 0
@assert var > 0.0
@assert ρ >= 0.0
@assert ρ < 1.0
#var= var*(1-ρ^2)^(1/2)
if method == "rouwenhorst"
MC = rouwenhorst(n, ρ,var)
return(P = MC.p, ϵ = exp.(MC.state_values))
elseif method == "tauchen"
MC = tauchen(n, ρ, var,0.0, 3)
return(P = MC.p, ϵ = exp.(MC.state_values))
elseif method == "SU" && n_y == 200
P = readdlm("P.csv", ',', Float64)
ygrid = readdlm("y.csv", ',', Float64)
ϵ = exp.(ygrid)
return (P=P, ϵ = ϵ )
else
throw(DomainError(method, "this method is not supported, try tauchen, rouwenhorst or SU if n_y ==200 "))
end
end
function unpack_params(non_calib, calib, grid_p) #pretty ugly way to unpack params, probably code would be faster without globals but for now speed is not an issue (for float)
@unpack σ, α, a, ζ, y_t, ρ, σ_μ, r, θ,h_bar = non_calib
@unpack β,δ_1,δ_2,w_bar, pen, k = calib
@unpack n_y, n_B, n_d, B_min, B_max, d_min, d_max = grid_p
global σ = σ
global a = a
global ζ = ζ
global α = α
global y_t = y_t
global ρ = ρ
global σ_μ = σ_μ
global r = r
global θ = θ
global h_bar = h_bar
global β = β
global δ_1 = δ_1
global δ_2 = δ_2
global w_bar = w_bar
global pen = pen
global k = k
global n_y = n_y
global n_B = n_B
global B_min = B_min
global B_max = B_max
global grid_B = B_min:(B_max-B_min)/(n_B-1):B_max
global n_d = n_d
global d_min = d_min
global d_max = d_max
global grid_d = d_min:(d_max-d_min)/(n_d-1):d_max
global P_stat, y_t_stat = DiscretizeAR(ρ, σ_μ, n_y, "tauchen")
global c_t_min = (copy(w_bar)/(copy(α)*(1-copy(a))/copy(a)))^(ζ)
end
function final_good(c_t, c_n) #final good aggregation
return (a*c_t^(1.0-1.0/ζ)+(1.0-a)*c_n^(1.0-1.0/ζ))^(1.0/(1.0-1.0/ζ))
end
function utilityCRRA(c) #CRRA utility
x = max(c, 1e-6)
if σ ==1
return log(x)
end
return (x^(1.0-σ)-1.0)/(1.0-σ)
end
function marg_utilityCRRA(c, σ) #not used so far
return c^(-σ)
end
function L(y_t) #penalty function for default
#return max(δ_1*y_t + δ_2*y_t^2.0,0.0)
return max(δ_1 + δ_2*log(y_t),0.0)
end
function q_d(d)
return 1/(1+r+k*d)
end
function c_n_peg(c_t)
if(ERR_glob == "float")
c_n = 1.0
return c_n
end
const_w = (α*(1.0-a)/a/w_bar)^(1.0/(1.0/ζ - (1.0-α)/α))
power = copy(1.0/ζ/(1.0/ζ - (1.0-α)/α))
c_n = max(min(const_w*c_t^power,1.0),1e-6)
return c_n
end
function mc_sample_path(P; init = 11, sample_size = 11000) #Simulate the Markov chain for the simulation
@assert size(P)[1] == size(P)[2] # square required
N = size(P)[1] # should be square
# create vector of discrete RVs for each row
dists = [Categorical(P[i, :]) for i in 1:N]
# setup the simulation
X = fill(0, sample_size) # allocate memory, or zeros(Int64, sample_size)
init_prob = fill(1/N, N)
X[1] = rand(Categorical(init_prob)) # set the initial state
for t in 2:sample_size
dist = dists[X[t-1]] # get discrete RV from last state's transition distribution
X[t] = rand(dist) # draw new value
end
SIM = convert(Array{Int64},X)
return SIM
end
#simulate if the country continue to be exclulded after default
function simulate_exclusion(θ)
dists = Categorical([θ , 1.0- θ])
sim = rand(dists, 1)
return sim[1]
end
#####################################################
#functions for global optimization
#####################################################
function interp_alg_const(splines_v, spline_q, state_y,state_b,state_d, x)
"""
interpolate the value of choosing debt b, given:
value functions (splines_v),
price function (spline_q),
endowment: state_y
current debt: state_b
"""
b= x[1]
d = x[2]
#this is version for float so far
q_b = min(max(spline_q(b,d), 0.0),1.0/(1.0+r)) #compute debt price
if b<=0
q_b =1.0/(1.0+r)
end
c_t = -state_b - state_d+ y_t_stat[state_y] +q_b*b+q_d(d)*d #compute tradeable consumption (check if it's >=0)
if(c_t<=0)
c_t = 1e-7
end
if( c_t < c_t_min)
c_n = (1.0-pen)*copy(c_n_peg(c_t)) #compute the consumption equivalent utility decrease (it does not mess with FOC)
else
c_n = (1.0-pen)
end
#compute the consumption with b
c = final_good(c_t, c_n)
val =0.0
val = copy(utilityCRRA(c))
#compute the next period's values
for j in 1:n_y
val = copy(val) + β*P_stat[state_y, j]*splines_v[j](b,d)
end
return -1.0*val #minimizing function, so need a negative value
end
function interp_alg_const_def(splines_v, splines_v_d, state_y,state_d, x)
"""
interpolate the value of choosing debt b, given:
value functions (splines_v),
price function (spline_q),
endowment: state_y
current debt: state_b
"""
d= x[1]
#this is version for float so far
c_t = -state_d + y_t_stat[state_y] + q_d(d)*d #compute tradeable consumption (check if it's >=0)
if(c_t<=0)
c_t = 1e-6
end
if( c_t < c_t_min) #compute the consumption equivalent utility decrease (it does not mess with FOC)
c_n = (1.0-pen)*copy(c_n_peg(c_t))
else
c_n =(1.0-pen)
end
#compute the consumption with b
c = final_good(c_t, c_n)
val = 0.0
#compute the next period's values
for j in 1:n_y
val = copy(val) + β*P_stat[state_y, j]*(θ*splines_v[j](0.0,d) +(1.0-θ)*splines_v_d[j](d))
end
val = copy(utilityCRRA(c)) - copy(L(y_t_stat[state_y]))+copy(val)
return -1.0*val #minimizing function, so need a negative value
end
function interp_alg_const_noIMF(splines_v, spline_q, state_y,state_b,state_d, x)
"""
interpolate the value of choosing debt b, given:
value functions (splines_v),
price function (spline_q),
endowment: state_y
current debt: state_b
"""
b= x[1]
#this is version for float so far
q_b = min(max(spline_q(b,0), 0.0),1.0/(1.0+r)) #compute debt price
if b<=0
q_b =1.0/(1.0+r)
end
c_t = -state_b - state_d+ y_t_stat[state_y] +q_b*b #compute tradeable consumption (check if it's >=0)
if(c_t<=0)
c_t = 1e-7
end
if( c_t < c_t_min) #no utility decrease since no IFI debt
c_n = copy(c_n_peg(c_t))
else
c_n = 1.0
end
#compute the consumption with b
c = final_good(c_t, c_n)
val =0.0
val = copy(utilityCRRA(c))
#compute the next period's values
for j in 1:n_y
val = copy(val) + β*P_stat[state_y, j]*splines_v[j](b,0.0)
end
return -1.0*val #minimizing function, so need a negative value
end
####################################################################################
#Wrappers for the global optimization (define problem in NLopt library)
####################################################################################
function solve_const_prob(f, x_0)
opt = Opt(:LN_BOBYQA , 2) #LN_BOBYQA , LN_NEWUOA, LN_COBYLA
opt.lower_bounds = [grid_B[1], grid_d[1]]
opt.upper_bounds = [grid_B[n_B], grid_d[n_d]]
opt.xtol_rel = 1e-8
opt.min_objective = f
opt.maxeval = 2500
opt.initial_step = 1e-3 #(grid_B[n_B]-grid_B[1])/500.0
#inequality_constraint!(opt, (x,g)->c(x,g), 1e-8)
(minf,minx,ret) = NLopt.optimize(opt, x_0)
return (minf,minx,ret)
end
function solve_const_prob_2(f, x_0)
opt = Opt(:LN_COBYLA , 2) #LN_BOBYQA , LN_NEWUOA, LN_COBYLA
opt.lower_bounds = [grid_B[1], grid_d[1]]
opt.upper_bounds = [grid_B[n_B], grid_d[n_d]]
opt.xtol_rel = 1e-8
opt.min_objective = f
opt.maxeval = 2500
opt.initial_step = 1e-3 #(grid_B[n_B]-grid_B[1])/500.0
#inequality_constraint!(opt, (x,g)->c(x,g), 1e-8)
(minf,minx,ret) = NLopt.optimize(opt, x_0)
return (minf,minx,ret)
end
function solve_const_prob_1d(f, x_0)
opt = Opt(:LN_COBYLA, 1) #LN_BOBYQA , LN_NEWUOA, LN_COBYLA
opt.lower_bounds = [grid_d[1]]
opt.upper_bounds = [grid_d[n_d]]
opt.xtol_rel = 1e-8
opt.min_objective = f
opt.maxeval = 2500
opt.initial_step = 1e-3
#inequality_constraint!(opt, (x,g)->c(x,g), 1e-8)
(minf,minx,ret) = NLopt.optimize(opt, x_0)
return (minf,minx,ret)
end
function solve_const_prob_1b(f, x_0)
opt = Opt(:LN_COBYLA, 1) #LN_BOBYQA , LN_NEWUOA, LN_COBYLA
opt.lower_bounds = [grid_B[1]]
opt.upper_bounds = [grid_B[n_B]]
opt.xtol_rel = 1e-8
opt.min_objective = f
opt.maxeval = 2500
opt.initial_step = 1e-3
#inequality_constraint!(opt, (x,g)->c(x,g), 1e-8)
(minf,minx,ret) = NLopt.optimize(opt, x_0)
return (minf,minx,ret)
end
############################################################################################
#global max procedures
##########################################################################################
function global_max(f, q_splines,x_guess; loc_flag =1.0)
if(loc_flag==1.0)
x_0_1s = [0.0, 0.00]
x_guess = [0.0,0.0]
g = ones(2)
max_glob = f(x_0_1s,g )
x_guess[2] = min(x_guess[2], grid_d[n_d])
#first stage
val_proposals = 1000*ones(4)
maximizer_proposals = zeros(2,4)
#look for the possible max on the whole grid
grid_id = grid_d[1]:(grid_d[n_d]-grid_d[1])/20: grid_d[n_d]
grid_i = grid_B[1]:(grid_B[n_B]-grid_B[1])/40: grid_B[n_B]
for ki in 1:length(grid_i)
for kid in 1:length(grid_id)
if f([grid_i[ki],grid_id[kid]],g)< max_glob
x_0_1s = copy([grid_i[ki],grid_id[kid]])
max_glob = f([grid_i[ki],grid_id[kid]],g)
end
end
end
#second stage
#set kid and look for the optimal ki
ff(x_b) = f([x_b,x_0_1s[2]], [0.1, 0.1])
qq(b) = min(q_splines(b, x_0_1s[2]),1.0/(1.0+r))
sol_max_qB = Optim.optimize(x-> -qq(x)*x,grid_B[1], grid_B[n_B], GoldenSection())
max_qB = Optim.minimizer(sol_max_qB)[1]
sol_2s = Optim.optimize(ff, grid_B[1], max_qB, GoldenSection())
x_0_2s = Optim.minimizer(sol_2s)[1]
# #third stage
(val_proposals[1],maximizer_proposals[:,1],ret) = solve_const_prob(f,[x_0_1s[1],x_0_1s[2]] )
(val_proposals[3],maximizer_proposals[:,3],ret2) = solve_const_prob(f, [x_0_2s,x_0_1s[2]] )
val_proposals[isnan.(val_proposals)].=Inf
(minf, ind) = findmin(val_proposals)
if(minf>max_glob)
println("second_shot")
(minf,minx,ret) = solve_const_prob(f, [0.0, 0.01] )
if(minf>max_glob)
(minf,minx,ret) = solve_const_prob_2(f, [0.0, 0.01] )
println("third_shot")
if(minf>max_glob)
minf = copy(max_glob)
solve_const_prob_2(f, [0.0, 0.01] )
println("mistake")
end
end
end
@assert minf == minimum(val_proposals)
minx = maximizer_proposals[:,ind]
return (minf,minx,ret)
else
(minf,minx,ret) = solve_const_prob_2(f,x_guess )
return (minf,minx,ret)
end
end
#same global maximization but duruing default
function global_max_def(f, x_guess; loc_flag =1.0)
if(loc_flag==1.0)
x_0 = [0.0]
g = ones(1)
max_glob = f(x_0,g )
grid_id = grid_d[1]:(grid_d[n_d]-grid_d[1])/60: grid_d[n_d]
for kid in 1:length(grid_id)
if f([grid_id[kid]],g)< max_glob
x_0 = copy([grid_id[kid]])
max_glob = f(x_0,g)
end
end
#second stage
(minf,minx,ret) = solve_const_prob_1d(f,x_0)
if(minf>max_glob)
(minf,minx,ret) = (max_glob, x_0, 1)
end
else
(minf,minx,ret) = solve_const_prob_1d(f,[x_guess] )
end
return (minf,minx,ret)
end
#global maximization withpout IFI debt
function global_max_noIMF(f, x_guess; loc_flag =1.0)
if(loc_flag==1.0)
x_0 = [0.0]
g = ones(1)
max_glob = f(x_0,g )
grid_iB = grid_B[1]:(grid_B[n_B]-grid_B[1])/150: grid_B[n_B]
for i in 1:length(grid_iB)
if f([grid_iB[i]],g)< max_glob
x_0 = copy([grid_iB[i]])
max_glob = f(x_0,g)
end
end
#second stage
(minf,minx,ret) = solve_const_prob_1b(f,x_0)
if(minf>max_glob)
(minf,minx,ret) = (max_glob, x_0, 1)
end
else
(minf,minx,ret) = solve_const_prob_1b(f,[x_guess])
end
return (minf,minx,ret)
end
###############################################################################################
#Value function iterations
###############################################################################################
#Solve the bellman equation via finite time approximation
function Solve_eq_peg2D(T)
#define the process for discretization
global P_stat, y_t_stat = DiscretizeAR(ρ, σ_μ, n_y, "tauchen")
#allocate memory
n_B_q = 2*n_B
n_d_q = 2*n_d
grid_B_q = grid_B[1]: (grid_B[n_B]- grid_B[1])/(n_B_q-1):grid_B[n_B]
grid_d_q = grid_d[1]: (grid_d[n_d]- grid_d[1])/(n_d_q-1):grid_d[n_d]
v_f = zeros(T, n_y, n_B, n_d)
v_c = zeros(T, n_y, n_B, n_d)
v_d = zeros(T, n_y, n_d)
q = zeros(T, n_y, n_B, n_d)
c_t = zeros(T, n_y, n_B, n_d)
c_n = ones(T, n_y, n_B, n_d)
c = zeros(T, n_y, n_B, n_d)
d = zeros(T, n_y, n_B, n_d)
policy_d = zeros(T, n_y, n_B, n_d)
policy_def = zeros(T, n_y, n_d)
policy_B = zeros(T, n_y, n_B, n_d)
default_border = zeros( n_y, n_d)
#define spline matrix
V_f_spline = Array{Interpolations.ScaledInterpolation}(undef,T,n_y)
V_c_spline = Array{Interpolations.ScaledInterpolation}(undef,T,n_y)
V_d_spline = Array{Interpolations.ScaledInterpolation}(undef,T,n_y)
q_spline = Array{Interpolations.ScaledInterpolation}(undef,T, n_y)
d_itp = Array{Interpolations.Extrapolation}(undef,T, n_y)
#define x_0 and max func
x_0 = zeros(2,n_y)
max_func = Array{Function}(undef,n_y)
#define vector of solutions
minf = zeros(n_y)
minx = zeros(2,n_y)
minf_IMF = zeros(n_y)
minx_IMF = zeros(2,n_y)
minf_noIMF = zeros(n_y)
minx_noIMF = zeros(n_y)
#start the loop for the last period
for j in 1:n_y
for i in 1:n_B
for id in 1:n_d
# check unconstrained case
c_t_c = max(y_t_stat[j]-grid_d[id] - grid_B[i],1e-7)
if(c_t_c<c_t_min)
c_n_c = c_n_peg(c_t_c)
else
c_n_c = 1.0
end
c_c = final_good(c_t_c, c_n_c)
c_t_d = max(y_t_stat[j]-grid_d[id],1e-7)
if(c_t_d<c_t_min)
c_n_d = c_n_peg(c_t_d)
else
c_n_d = 1.0
end
c_d = final_good(c_t_d,c_n_d)
if utilityCRRA(c_c)>utilityCRRA(c_d)-L(y_t_stat[j])
c_t[T,j,i,id] = c_t_c
c_n[T,j,i,id] = c_n_c
c[T,j,i,id] = c_c
v_f[T,j,i,id] = utilityCRRA(c[T,j,i,id])
else
c_t[T,j,i,id] = c_t_d
c_n[T,j,i,id] = c_n_d
c[T,j,i,id] = c_d
d[T,j,i,id] = 1.0
v_f[T,j,i,id] = utilityCRRA(c[T,j,i,id]) -L(y_t_stat[j])
end
v_c[T,j,i,id] = utilityCRRA(c_c)
v_d[T,j,id] = utilityCRRA(c_d)-L(y_t_stat[j])
end
end
end
println(sum(d[T,:,:,:]))
##ITERTAIONS STARTS
flag = 1.0
for t in T-1:-1:1
for j in 1:n_y
V_f_spline[t+1,j ] = Interpolations.scale(interpolate(v_f[t+1,j,:,:], BSpline(Cubic(Line(OnGrid())))), grid_B, grid_d)
V_c_spline[t+1,j ] = Interpolations.scale(interpolate(v_c[t+1,j,:,:], BSpline(Cubic(Line(OnGrid())))), grid_B, grid_d)
V_d_spline[t+1, j] = Interpolations.scale(interpolate(v_d[t+1,j,:], BSpline(Cubic(Line(OnGrid())))), grid_d)
#CubicSplineInterpolation((grid_B, grid_d), v_f[t+1,j,:,:],extrapolation_bc = Line())
end
for j in 1:n_y
for i in 1:n_B
for id in 1:n_d
d_val = 0.0
for jj in 1:n_y
d_val = copy(d_val)+ P_stat[j,jj]*d[t+1,jj,i,id]
end
q[t,j,i,id] = 1.0/(1.0+r)*(1.0-copy(d_val))
end
end
end
for j in 1:n_y
q_spline[t, j] = Interpolations.scale(interpolate(q[t,j,:,:], BSpline(Interpolations.Linear())), grid_B, grid_d)
end
Threads.@threads for j in 1:n_y
for id in 1:n_d
#compute default value
x_0_def = max(min(policy_def[t+1,j,id], grid_d[n_d]),grid_d[1])
func_def(x::Vector, grad::Vector) = deepcopy(interp_alg_const_def(copy(V_f_spline[t+1,:]),copy(V_d_spline[t+1,:]), j ,grid_d[id],x))
(minf_def,minx_def,ret_def) = global_max_def(func_def, x_0_def, loc_flag = flag) #solve_const_prob(interp_alg_unconst_1, constraint, x_0)
c_t_d = max(y_t_stat[j] -grid_d[id],1e-6)
val_d = 0.0
for jj in 1:n_y
val_d = copy(val_d)+ P_stat[j,jj]*β*(θ*V_f_spline[t+1,jj ](0.0,0.0)+ (1-θ)*v_d[t+1, jj,1]) #TODO
end
if(c_t_d< c_t_min)
c_n_d = c_n_peg(c_t_d)
else
c_n_d = 1.0
end
if utilityCRRA(final_good(c_t_d, c_n_d)) - L(y_t_stat[j])+ val_d > - minf_def
v_d[t,j,id] = utilityCRRA(final_good(c_t_d, c_n_d)) - L(y_t_stat[j])+ val_d
policy_def[t,j, id] = 0.0
else
policy_def[t,j, id] = minx_def[1]
v_d[t,j,id] = -minf_def
end
#compute continuation
for i in 1:n_B
if(t==T-1 )
x_0[:,j] = [0.0001,0.0]
else
x_0[:,j] = [max(min(policy_B[t+1,j,i,id], grid_B[n_B]),grid_B[1]), max(min(policy_d[t+1,j,i,id], grid_d[n_d]), grid_d[1])]
end
#define the maximized functions for both cases (with IFI debt and without)
func_IMF(x::Vector, grad::Vector) = deepcopy(interp_alg_const(copy(V_f_spline[t+1,:]), q_spline[t,j], j ,grid_B[i],grid_d[id],x))
func_noIMF(x::Vector, grad::Vector) = deepcopy(interp_alg_const_noIMF(copy(V_f_spline[t+1,:]), q_spline[t,j], j ,grid_B[i],grid_d[id],x))
(minf_IMF[j],minx_IMF[:,j],ret_IMF) = global_max(func_IMF, q_spline[t,j],x_0[:,j], loc_flag = flag) #solve the problem with the IFI debt
(minf_noIMF[j],b_sol,ret_noIMF) = global_max_noIMF(func_noIMF ,x_0[1,j], loc_flag = flag) #solve the problem without IFI debt
minx_noIMF[j] = b_sol[1]
#compare values
if minf_noIMF[j]<minf_IMF[j]
v_f[t,j,i,id] = -minf_noIMF[j]
policy_d[t,j,i,id] = 0.0
policy_B[t,j,i,id] = minx_noIMF[j]
else
v_f[t,j,i,id] = -minf_IMF[j]
policy_d[t,j,i,id] = minx_IMF[2,j]
policy_B[t,j,i,id] = minx_IMF[1,j]
end
#println(maxim_sol)
if v_f[t,j,i,id] <= v_d[t, j,id]
v_f[t,j,i,id] = v_d[t, j,id]
d[t,j,i,id] = 1.0
end
end
end
end
if(mod(T-t, 10)==0)
println("Iteration: ", T-t)
println(maximum(abs.(v_f[t,:,:,:].-v_f[t+1,:,:,:])))
println(mean(abs.(v_f[t,:,:,:].-v_f[t+1,:,:,:])))
println(maximum(abs.(q[t,:,:,:].-q[t+1,:,:,:])))
println(sum(d[t,:,:,:]))
end
if(maximum(abs.(v_f[t,:,:,:].-v_f[t+1,:,:,:])) <=5e-2 && T-t>10) #+maximum(abs.(q[t,:,:,:].-q[t+1,:,:,:]))
flag =0.0
end
if(maximum(abs.(v_f[t,:,:,:].-v_f[t+1,:,:,:]))<=1e-5 || t==1) #stop iterations
v_f[1,:,:,:] = v_f[t,:,:,:]
q[1,:,:,:] = q[t,:,:,:]
policy_d[1,:,:,:] =policy_d[t,:,:,:]
policy_B[1,:,:,:] = policy_B[t,:,:,:]
d[1,:,:,:] = d[t,:,:,:]
v_d[1,:,:] = v_d[t,:,:]
policy_def[1,:,:] = policy_def[t,:,:]
for j in 1:n_y
V_f_spline[1,j ] = Interpolations.scale(interpolate(v_f[t,j,:,:], BSpline(Cubic(Line(OnGrid())))), grid_B, grid_d)
#CubicSplineInterpolation((grid_B, grid_d), v_f[t+1,j,:,:],extrapolation_bc = Line())
q_spline[1, j] = Interpolations.scale(interpolate(q[t,j,:,:], BSpline(Cubic(Line(OnGrid())))), grid_B, grid_d)
#LinearInterpolation((grid_B, grid_d), q[t,j,:,:],extrapolation_bc = Periodic()) #spline works very bad for the price function (as they are non-monotonic)
end
break
end
end
#compute an exact default region
for j in 1:n_y
for id in 1:n_d
if abs(v_f[1,j,1, id]-v_d[1, j, id])<= 1e-6
default_border[j, id] = 0.0+1e-6
elseif v_f[1,j,n_B, id]-v_d[1, j, id]>1e-6
default_border[j, id] = grid_B[n_B]+0.2 #never will be chosen
else
f_def_bord(x) = V_f_spline[1,j](x, grid_d[id])- v_d[1, j, id]-1e-6
default_border[j, id] = Roots.find_zero(f_def_bord, (grid_B[1], grid_B[n_B] ))
end
end
end
return (q[1,:,:,:], d[1,:,:,:], policy_B[1,:,:,:], policy_d[1,:,:,:], v_f[1,:,:,:],default_border, v_d[1,:,:], policy_def[1,:,:] )
end
########################################################################################################################
#simulate economy
#########################################################################################################################
function simulate_eq_2D( Model_solution; burnout = 1000, t_sim =1200, n_sim = 10000, ERR="float", method = "spline_sch")
global P_stat, y_t_stat = DiscretizeAR(ρ, σ_μ, n_y, "tauchen")
#unpack policy functions and paramters
n_B_long =10000
q = Model_solution[1]
#Def_mat = Model_solution[2]
Policy_B = Model_solution[3]
Policy_d = Model_solution[4]
Def_bord = Model_solution[6]
Policy_def = Model_solution[8]
grid_B_long = grid_B[1]:(grid_B[n_B] - grid_B[1])/(n_B_long-1):grid_B[n_B]
Def_matrix = zeros(n_y, n_B_long, n_d)
for j in 1:n_y
for id in 1:n_d
for i in 1:n_B_long
if(Def_bord[j,id]>= grid_B_long[i])
Def_matrix[j,i,id] =1.0
end
end
end
end
#allocate memory
SIM = zeros(Int64, n_sim, t_sim) #simulated income process
B_hist = zeros(n_sim, t_sim) #private debt history
d_hist = zeros(n_sim, t_sim) #assets history for the non-defautable debt
Y_t = zeros(n_sim, t_sim) # output history
Trade_B = zeros(n_sim, t_sim) # trade balance history
C_t = zeros(n_sim, t_sim) # consumption history tradeables
C_n = ones(n_sim, t_sim) # non-tradeables
h_t = ones(n_sim, t_sim)
C = zeros(n_sim, t_sim) # final good
D = zeros(n_sim, t_sim) #Defaults histiry
D_state = zeros(n_sim, t_sim) #exclusion from the financial market histiry
R = zeros(n_sim, t_sim) #q hiatory
R_d = zeros(n_sim, t_sim)
#exchange rate and minimal wage
ϵ = ones(n_sim, t_sim)
const_w = (α*(1.0-a)/a/w_bar)^(1.0/(1.0/ζ - (1.0-α)/α))
power = copy(1.0/ζ/(1.0/ζ - (1.0-α)/α))
policy_B_spline = Array{Interpolations.ScaledInterpolation}(undef,n_y)
policy_d_spline = Array{Interpolations.ScaledInterpolation}(undef,n_y)
policy_def_spline = Array{Interpolations.ScaledInterpolation}(undef,n_y)
q_spline = Array{Interpolations.ScaledInterpolation}(undef, n_y)
Def_bord_itp = Array{Interpolations.Extrapolation}(undef,n_y)
#interpolate policy functions
for j in 1:n_y
q_spline[j] = Interpolations.scale(interpolate(q[j,:,:], BSpline(Cubic(Line(OnGrid())))), grid_B, grid_d)
policy_B_spline[j] = Interpolations.scale(interpolate(Policy_B[j,:,:], BSpline(Cubic(Line(OnGrid())))), grid_B, grid_d)
policy_d_spline[j] = Interpolations.scale(interpolate(Policy_d[j,:,:], BSpline(Cubic(Line(OnGrid())))), grid_B, grid_d)
policy_def_spline[j] = Interpolations.scale(interpolate(Policy_def[j,:], BSpline(Cubic(Line(OnGrid())))), grid_d)
Def_bord_itp[j] = LinearInterpolation((grid_B_long, grid_d), Def_matrix[j,:,:], extrapolation_bc = Periodic()) #def bord is given for a id points co that is why I change the
end
#define starting values
y_0 = Int(floor(n_y/2) ) # start with 11th state
Y_0 = y_t_stat[y_0]*ones(n_sim) #output start value
B_0 = zeros(n_sim) #start with 0 assets
d_0 = zeros(n_sim)
Y_t[:,1] = Y_0
B_hist[:,1] = B_0
d_hist[:,1] = d_0
Default_flag = 0.0 # flag if the country was excluded from financial market in the previous period
#simulate income process
for i in 1:n_sim
SIM[i,:] = mc_sample_path(P_stat,init = Int(floor(n_y/2) ), sample_size = t_sim)
end
#now use simulated income process to find trade balance, output, assets and q history
for i in 1:n_sim
for t in 2:t_sim
#case when country was excluded from financial market in the previous period
if(Default_flag==1.0)
simi = simulate_exclusion(θ)
if(simi==1)
Default_flag = 0.0
else
Default_flag = 1.0
end
if(Default_flag==1.0)
Y_t[i,t] = y_t_stat[SIM[i,t]]
d_hist[i,t] = min(max(policy_def_spline[SIM[i,t]](d_hist[i,t-1]), grid_d[1]), grid_d[n_d])
C_t[i,t] = Y_t[i,t] + q_d(d_hist[i,t])*d_hist[i,t] - d_hist[i,t-1]
if d_hist[i,t]>1e-6
if C_t[i,t] < c_t_min && ERR =="peg"
C_n[i,t] = max(min(copy(C_t[i,t])^(power)*const_w,1.0),1e-6)
h_t[i,t] = C_n[i,t]^(1.0/α)
else
C_n[i,t] = 1.0 - pen
end
R_d[i,t] = 1.0/q_d(d_hist[i,t]) -1.0
else
if C_t[i,t] < c_t_min && ERR =="peg"
C_n[i,t] = max(min(copy(C_t[i,t])^(power)*const_w,1.0),1e-6)
h_t[i,t] = C_n[i,t]^(1.0/α)
else
C_n[i,t] = 1.0 - pen
end
R_d[i,t] = -1.0
end
C[i,t] = final_good(C_t[i,t],C_n[i,t])
Trade_B[i,t] = (Y_t[i,t] - C_t[i,t])/Y_t[i,t]
B_hist[i,t] = 0.0
R[i,t] = -1.0 #nop interest rate
D[i,t] = 0.0
D_state[i,t] = 1.0
else
Y_t[i,t] = y_t_stat[SIM[i,t]]
B_hist[i,t] = max(policy_B_spline[SIM[i,t]](0.0, d_hist[i,t-1] ), grid_B[1])
d_hist[i,t] = min(max(policy_d_spline[SIM[i,t]](0.0, d_hist[i,t-1]),0.0), grid_d[n_d])
C_t[i,t] = Y_t[i,t] + q_spline[SIM[i,t]](B_hist[i,t], d_hist[i,t])*B_hist[i,t] + q_d(d_hist[i,t])*d_hist[i,t] - d_hist[i,t-1]
if d_hist[i,t]>1e-6
if C_t[i,t] < c_t_min && ERR =="peg"
C_n[i,t] = max(min(copy(C_t[i,t])^(power)*const_w,1.0),1e-6)
h_t[i,t] = C_n[i,t]^(1.0/α)
else
C_n[i,t] = 1.0 - pen
end
R_d[i,t] = 1.0/q_d(d_hist[i,t]) -1.0
else
if C_t[i,t] < c_t_min && ERR =="peg"
C_n[i,t] = max(min(copy(C_t[i,t])^(power)*const_w,1.0),1e-6)
h_t[i,t] = C_n[i,t]^(1.0/α)
else
C_n[i,t] = 1.0 - pen
end
R_d[i,t] = -1.0
end
C[i,t] = final_good(C_t[i,t], C_n[i,t])
if(B_hist[i,t]>1e-6)
R[i,t] = 1.0/q_spline[SIM[i,t]](B_hist[i,t], d_hist[i,t]) - 1.0
else
R[i,t] = -1
end
D[i,t] = 0.0
D_state[i,t] = 0.0
Trade_B[i,t] = (Y_t[i,t] - C_t[i,t])/Y_t[i,t]
Default_flag = 0.0
end
else
if Def_bord_itp[SIM[i,t]](B_hist[i,t-1],d_hist[i,t-1] ) <1.0 #case of default
Y_t[i,t] = y_t_stat[SIM[i,t]]
d_hist[i,t] = min(max(policy_def_spline[SIM[i,t]](d_hist[i,t-1]), grid_d[1]), grid_d[n_d])
C_t[i,t] = Y_t[i,t] - d_hist[i,t-1] + q_d(d_hist[i,t])*d_hist[i,t]
C[i,t] = final_good(C_t[i,t],1.0)
if d_hist[i,t]>1e-6
if C_t[i,t] < c_t_min && ERR =="peg"
C_n[i,t] = max(min(copy(C_t[i,t])^(power)*const_w,1.0),1e-6)
h_t[i,t] = C_n[i,t]^(1.0/α)
else
C_n[i,t] = 1.0
end
R_d[i,t] = 1.0/q_d(d_hist[i,t]) -1.0
else
if C_t[i,t] < c_t_min && ERR =="peg"
C_n[i,t] = max(min(copy(C_t[i,t])^(power)*const_w,1.0),1e-6)
h_t[i,t] = C_n[i,t]^(1.0/α)
else
C_n[i,t] = 1.0
end
R_d[i,t] = -1.0
end
C[i,t] = final_good(C_t[i,t],C_n[i,t])
B_hist[i,t] = 0.0
R[i,t] = -1.0 #1.0/q[SIM[i,t],A_int[i,t]] - 1.0
D[i,t] = 1.0
D_state[i,t] = 1.0
Default_flag = 1.0
Trade_B[i,t] = (Y_t[i,t] - C_t[i,t])/Y_t[i,t]
else
Y_t[i,t] = y_t_stat[SIM[i,t]]
B_hist[i,t] = max(min(policy_B_spline[SIM[i,t]](B_hist[i,t-1], d_hist[i,t-1]), grid_B[n_B]), grid_B[1])
d_hist[i,t] = min(max(policy_d_spline[SIM[i,t]](B_hist[i,t-1], d_hist[i,t-1]),0.0), grid_d[n_d])
C_t[i,t] =max(Y_t[i,t]- B_hist[i,t-1] - d_hist[i,t-1]+ q_spline[SIM[i,t]](0.0, 0.0)*B_hist[i,t] + q_d(d_hist[i,t])*d_hist[i,t], 1e-6)
if d_hist[i,t]>1e-6
if C_t[i,t] < c_t_min && ERR =="peg"
C_n[i,t] = max(min(copy(C_t[i,t])^(power)*const_w,1.0),1e-6)
h_t[i,t] = C_n[i,t]^(1.0/α)
else
C_n[i,t] = 1.0
end
R_d[i,t] = 1.0/q_d(d_hist[i,t]) - 1.0
else
if C_t[i,t] < c_t_min && ERR =="peg"
C_n[i,t] = max(min(copy(C_t[i,t])^(power)*const_w,1.0),1e-6)
h_t[i,t] = C_n[i,t]^(1.0/α)
else
C_n[i,t] = 1.0
end
R_d[i,t] = - 1.0
end
C[i,t] = final_good(C_t[i,t], C_n[i,t])
if(B_hist[i,t]>1e-6)
R[i,t] = 1.0/q_spline[SIM[i,t]](B_hist[i,t], d_hist[i,t]) - 1.0
else
R[i,t] = -1
end
D[i,t] = 0.0
D_state[i,t] = 0.0
Trade_B[i,t] = (Y_t[i,t] - C_t[i,t])/Y_t[i,t]
Default_flag = 0.0
end
end
if α * (C_t[i,t])^(1.0/ζ)* (1.0-a)/a < w_bar && ERR == "float"
ϵ[i,t] = w_bar/((α * (C_t[i,t])^(1.0/ζ))* (1.0-a)/a)
end
end
end
#compute stats for defaults
n_defaults = sum(D[:, burnout:t_sim])
non_defaults = D_state[:,burnout:t_sim].<1.0
#default probability
Def_prob = 1.0 - (1.0-n_defaults/(n_sim*(t_sim-burnout)))^4.0
n_chosen_def = 10000
#stats after default:
Y_ab = Y_t[:,burnout:t_sim]
R_ab = R[:,burnout:t_sim]
R_d_ab = R_d[:,burnout:t_sim]
B_hist_ab = B_hist[:,burnout:t_sim]
d_hist_ab = d_hist[:,burnout:t_sim]