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authorGuillaume Horel <guillaume.horel@serenitascapital.com>2014-10-08 10:39:29 -0400
committerGuillaume Horel <guillaume.horel@serenitascapital.com>2014-10-08 10:39:29 -0400
commitf11771ed1191a9db78007aa3d7bca002bab0e0f6 (patch)
treec8787a4b07dd06ff79ac489b1245adbdc4b11754 /R/tranche_functions.R
parent1e2aea18da610f7f225a744c77081f6ced9379fe (diff)
downloadlossdistrib-f11771ed1191a9db78007aa3d7bca002bab0e0f6.tar.gz
rename file since there are no tranche functions left
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-## todo:
-## -investigate other ways to interpolate the random severities on the grid
-## I'm thinking that at eah severity that we add to the distribution, round it down
-## and keep track of the missing mass: namely if X_i=S_i w.p p_i, then add
-## X_i=lu*floor(S_i/lu) with probability p_i and propagate
-## X_{i+1}=S_{i+1}+(S_i-lu*floor(S_i/lu)) with the right probability
-## - investigate truncated distributions more (need to compute loss and recov distribution
-## separately, for the 0-10 equity tranche, we need the loss on the 0-0.1 support and
-## recovery with 0.1-1 support, so it's not clear that there is a big gain.
-## - do the correlation adjustments when computing the deltas since it seems to be
-## the market standard
-
-#' Gauss-Hermite quadrature weights
-#'
-#' \code{GHquad} computes the quadrature weights for integrating against a
-#' Gaussian distribution.
-#'
-#' if f is a function, then with(GHquad(100), crossprod(f(Z), w))
-#'
-#' @param n Integer, the number of nodes
-#' @return A list with two components:
-#' \item{Z}{the list of nodes}
-#' \item{w}{the corresponding weights}
-#'
-GHquad <- function(n){
- n <- as.integer(n)
- Z <- double(n)
- w <- double(n)
- result <- .C("GHquad", n, Z=Z, w=w)
- result[[1]] <- NULL
- return(result)
-}
-
-#' Loss distribution of a portfolio
-#'
-#' \code{lossdistrib} computes the probability distribution of a sum
-#' of independent Bernouilli variables with unequal probabilities.
-#'
-#' This uses the basic recursive algorithm of Andersen, Sidenius and Basu
-#' We compute the probability distribution of S = \sum_{i=1}^n X_i
-#' where X_i is Bernouilli(p_i)
-#' @param p Numeric vector, the vector of success probabilities
-#' @return A vector q such that q[k]=P(S=k)
-lossdistrib <- function(p){
- ## basic recursive algorithm of Andersen, Sidenius and Basu
- n <- length(p)
- q <- rep(0, (n+1))
- q[1] <- 1
- for(i in 1:n){
- q[-1] <- p[i]*q[-(n+1)]+(1-p[i])*q[-1]
- q[1] <- (1-p[i])*q[1]
- }
- return(q)
-}
-
-#' Loss distribution of a portfolio
-#'
-#' \code{lossdistrib.fft} computes the probability distribution of a sum
-#' of independent Bernouilli variables with unequal probabilities.
-#'
-#' This uses the fft. Complexity is of order O(n m) + O(m\log{m})
-#' where m is the size of the grid and n, the number of probabilities.
-#' It is slower than the recursive algorithm in practice.
-#' We compute the probability distribution of S = \sum_{i=1}^n X_i
-#' where X_i is Bernouilli(p_i)
-#' @param p Numeric vector, the vector of success probabilities
-#' @return A vector such that q[k]=P(S=k)
-lossdistrib.fft <- function(p){
- n <- length(p)
- theta <- 2*pi*1i*(0:n)/(n+1)
- Phi <- 1 - p + p%o%exp(theta)
- v <- apply(Phi, 2, prod)
- return(1/(n+1)*Re(fft(v)))
-}
-
-#' recursive algorithm with first order correction
-#'
-#' @param p Numeric, vector of default probabilities
-#' @param w Numeric, vector of weights
-#' @param S Numeric, vector of severities
-#' @param N Integer, number of ticks in the grid
-#' @param defaultflag Boolean, if True, we compute the default distribution
-#' (instead of the loss distribution).
-#' @return a Numeric vector of size \code{N} computing the loss (resp.
-#' default) distribution if \code{defaultflag} is FALSE (resp. TRUE).
-lossdistrib2 <- function(p, w, S, N, defaultflag=FALSE){
- n <- length(p)
- lu <- 1/(N-1)
- q <- rep(0, N)
- q[1] <- 1
- for(i in 1:n){
- if(defaultflag){
- d <- w[i] /lu
- }else{
- d <- S[i] * w[i] / lu
- }
- d1 <- floor(d)
- d2 <- ceiling(d)
- p1 <- p[i]*(d2-d)
- p2 <- p[i] - p1
- q1 <- c(rep(0,d1), p1*q[1:(N-d1)])
- q2 <- c(rep(0,d2), p2*q[1:(N-d2)])
- q <- q1 + q2 + (1-p[i])*q
- }
- q[length(q)] <- q[length(q)]+1-sum(q)
- return(q)
-}
-
-lossdistrib2.truncated <- function(p, w, S, N, cutoff=N){
- ## recursive algorithm with first order correction
- ## p vector of default probabilities
- ## w vector of weigths
- ## S vector of severities
- ## N number of ticks in the grid (for best accuracy should
- ## be a multiple of the number of issuers)
- ## cutoff where to stop computing the exact probabilities
- ## (useful for tranche computations)
-
- ## this is actually slower than lossdistrib2. But in C this is
- ## twice as fast.
- ## for high severities, M can become bigger than N, and there is
- ## some probability mass escaping.
- n <- length(p)
- lu <- 1/(N-1)
- q <- rep(0, truncated)
- q[1] <- 1
- M <- 1
- for(i in 1:n){
- d <- S[i] * w[i] / lu
- d1 <- floor(d)
- d2 <- ceiling(d)
- p1 <- p[i]*(d2-d)
- p2 <- p[i] - p1
- q1 <- p1*q[1:min(M, cutoff-d1)]
- q2 <- p2*q[1:min(M, cutoff-d2)]
- q[1:min(M, cutoff)] <- (1-p[i])*q[1:min(M, cutoff)]
- q[(d1+1):min(M+d1, cutoff)] <- q[(d1+1):min(M+d1, cutoff)]+q1
- q[(d2+1):min(M+d2, cutoff)] <- q[(d2+1):min(M+d2, cutoff)]+q2
- M <- M+d2
- }
- return(q)
-}
-
-recovdist <- function(dp, pp, w, S, N){
- ## computes the recovery distribution for a sum of independent variables
- ## R=\sum_{i=1}^n w[i] X_i
- ## where X_i = 0 w.p 1 - dp[i] - pp[i]
- ## = 1 - S[i] w.p dp[i]
- ## = 1 w.p pp[i]
- ## each non zero value v is interpolated on the grid as
- ## the pair of values floor(v/lu) and ceiling(v/lu) so that
- ## X_i has four non zero values
- n <- length(dp)
- q <- rep(0, N)
- q[1] <- 1
- lu <- 1/(N-1)
- for(i in 1:n){
- d1 <- w[i]*(1-S[i])/lu
- d1l <- floor(d1)
- d1u <- ceiling(d1)
- d2 <- w[i] / lu
- d2l <- floor(d2)
- d2u <- ceiling(d2)
- dp1 <- dp[i] * (d1u-d1)
- dp2 <- dp[i] - dp1
- pp1 <- pp[i] * (d2u - d2)
- pp2 <- pp[i] - pp1
- q1 <- c(rep(0, d1l), dp1 * q[1:(N-d1l)])
- q2 <- c(rep(0, d1u), dp2 * q[1:(N-d1u)])
- q3 <- c(rep(0, d2l), pp1 * q[1:(N-d2l)])
- q4 <- c(rep(0, d2u), pp2 *q[1:(N-d2u)])
- q <- q1+q2+q3+q4+(1-dp[i]-pp[i])*q
- }
- return(q)
-}
-
-lossdist.joint <- function(p, w, S, N, defaultflag=FALSE){
- ## recursive algorithm with first order correction
- ## to compute the joint probability distribution of the loss and recovery
- ## inputs:
- ## p: vector of default probabilities
- ## w: vector of issuer weights
- ## S: vector of severities
- ## N: number of tick sizes on the grid
- ## defaultflag: if true computes the default distribution
- ## output:
- ## q: matrix of joint loss, recovery probability
- ## colSums(q) is the recovery distribution marginal
- ## rowSums(q) is the loss distribution marginal
- n <- length(p)
- lu <- 1/(N-1)
- q <- matrix(0, N, N)
- q[1,1] <- 1
- for(k in 1:n){
- if(defaultflag){
- x <- w[k] / lu
- }else{
- x <- S[k] * w[k]/lu
- }
- y <- (1-S[k]) * w[k]/lu
- i <- floor(x)
- j <- floor(y)
- weights <- c((i+1-x)*(j+1-y), (i+1-x)*(y-j), (x-i)*(y-j), (j+1-y)*(x-i))
- psplit <- p[k] * weights
- qtemp <- matrix(0, N, N)
- qtemp[(i+1):N,(j+1):N] <- qtemp[(i+1):N,(j+1):N] + psplit[1] * q[1:(N-i),1:(N-j)]
- qtemp[(i+1):N,(j+2):N] <- qtemp[(i+1):N,(j+2):N] + psplit[2] * q[1:(N-i), 1:(N-j-1)]
- qtemp[(i+2):N,(j+2):N] <- qtemp[(i+2):N,(j+2):N] + psplit[3] * q[1:(N-i-1), 1:(N-j-1)]
- qtemp[(i+2):N, (j+1):N] <- qtemp[(i+2):N, (j+1):N] + psplit[4] * q[1:(N-i-1), 1:(N-j)]
- q <- qtemp + (1-p[k])*q
- }
- q[length(q)] <- q[length(q)]+1-sum(q)
- return(q)
-}
-
-lossdist.prepay.joint <- function(dp, pp, w, S, N, defaultflag=FALSE){
- ## recursive algorithm with first order correction
- ## to compute the joint probability distribition of the loss and recovery
- ## inputs:
- ## dp: vector of default probabilities
- ## pp: vector of prepay probabilities
- ## w: vector of issuer weights
- ## S: vector of severities
- ## N: number of tick sizes on the grid
- ## defaultflag: if true computes the default
- ## outputs
- ## q: matrix of joint loss and recovery probability
- ## colSums(q) is the recovery distribution marginal
- ## rowSums(q) is the loss distribution marginal
- n <- length(dp)
- lu <- 1/(N-1)
- q <- matrix(0, N, N)
- q[1,1] <- 1
- for(k in 1:n){
- y1 <- (1-S[k]) * w[k]/lu
- y2 <- w[k]/lu
- j1 <- floor(y1)
- j2 <- floor(y2)
- if(defaultflag){
- x <- y2
- i <- j2
- }else{
- x <- y2-y1
- i <- floor(x)
- }
-
- ## weights <- c((i+1-x)*(j1+1-y1), (i+1-x)*(y1-j1), (x-i)*(y1-j1), (j1+1-y1)*(x-i))
- weights1 <- c((i+1-x)*(j1+1-y1), (i+1-x)*(y1-j1), (x-i)*(y1-j1), (j1+1-y1)*(x-i))
- dpsplit <- dp[k] * weights1
-
- if(defaultflag){
- weights2 <- c((i+1-x)*(j2+1-y2), (i+1-x)*(y2-j2), (x-i)*(y2-j2), (j2+1-y2)*(x-i))
- ppsplit <- pp[k] * weights2
- }else{
- ppsplit <- pp[k] * c(j2+1-y2, y2-j2)
- }
- qtemp <- matrix(0, N, N)
- qtemp[(i+1):N,(j1+1):N] <- qtemp[(i+1):N,(j1+1):N] + dpsplit[1] * q[1:(N-i),1:(N-j1)]
- qtemp[(i+1):N,(j1+2):N] <- qtemp[(i+1):N,(j1+2):N] + dpsplit[2] * q[1:(N-i), 1:(N-j1-1)]
- qtemp[(i+2):N,(j1+2):N] <- qtemp[(i+2):N,(j1+2):N] + dpsplit[3] * q[1:(N-i-1), 1:(N-j1-1)]
- qtemp[(i+2):N,(j1+1):N] <- qtemp[(i+2):N, (j1+1):N] + dpsplit[4] * q[1:(N-i-1), 1:(N-j1)]
- if(defaultflag){
- qtemp[(i+1):N,(j2+1):N] <- qtemp[(i+1):N,(j2+1):N] + ppsplit[1] * q[1:(N-i),1:(N-j2)]
- qtemp[(i+1):N,(j2+2):N] <- qtemp[(i+1):N,(j2+2):N] + ppsplit[2] * q[1:(N-i), 1:(N-j2-1)]
- qtemp[(i+2):N,(j2+2):N] <- qtemp[(i+2):N,(j2+2):N] + ppsplit[3] * q[1:(N-i-1), 1:(N-j2-1)]
- qtemp[(i+2):N,(j2+1):N] <- qtemp[(i+2):N, (j2+1):N] + ppsplit[4] * q[1:(N-i-1), 1:(N-j2)]
- }else{
- qtemp[, (j2+1):N] <- qtemp[,(j2+1):N]+ppsplit[1]*q[,1:(N-j2)]
- qtemp[, (j2+2):N] <- qtemp[,(j2+2):N]+ppsplit[2]*q[,1:(N-j2-1)]
- }
- q <- qtemp + (1-pp[k]-dp[k]) * q
- }
- q[length(q)] <- q[length(q)] + 1 - sum(q)
- return(q)
-}
-
-lossdistC <- function(p, w, S, N, defaultflag=FALSE){
- ## C version of lossdistrib2, roughly 50 times faster
- .C("lossdistrib", as.double(p), as.integer(length(p)),
- as.double(w), as.double(S), as.integer(N), as.logical(defaultflag), q = double(N))$q
-}
-
-lossdistCblas <- function(p, w, S, N, defaultflag=FALSE){
- ## C version of lossdistrib2, roughly 50 times faster
- .C("lossdistrib_blas", as.double(p), as.integer(length(p)),
- as.double(w), as.double(S), as.integer(N), as.logical(defaultflag), q = double(N))$q
-}
-
-lossdistCZ <- function(p, w, S, N, defaultflag=FALSE, rho, Z){
- #S is of size (length(p), length(Z))
- .C("lossdistrib_Z", as.double(p), as.integer(length(p)),
- as.double(w), as.double(S), as.integer(N), as.logical(defaultflag),
- as.double(rho), as.double(Z), as.integer(length(Z)),
- q = matrix(0, N, length(Z)))$q
-}
-
-lossdistC.truncated <- function(p, w, S, N, T=N){
- ## C version of lossdistrib2, roughly 50 times faster
- .C("lossdistrib_truncated", as.double(p), as.integer(length(p)),
- as.double(w), as.double(S), as.integer(N), as.integer(T), q = double(T))$q
-}
-
-recovdistC <- function(dp, pp, w, S, N){
- ## C version of recovdist
- .C("recovdist", as.double(dp), as.double(pp), as.integer(length(dp)),
- as.double(w), as.double(S), as.integer(N), q = double(N))$q
-}
-
-lossdistC.joint <- function(p, w, S, N, defaultflag=FALSE){
- ## C version of lossdistrib.joint, roughly 20 times faster
- .C("lossdistrib_joint", as.double(p), as.integer(length(p)), as.double(w),
- as.double(S), as.integer(N), as.logical(defaultflag), q = matrix(0, N, N))$q
-}
-
-lossdistC.jointblas <- function(p, w, S, N, defaultflag=FALSE){
- ## C version of lossdistrib.joint, roughly 20 times faster
- .C("lossdistrib_joint_blas", as.double(p), as.integer(length(p)), as.double(w),
- as.double(S), as.integer(N), as.logical(defaultflag), q = matrix(0, N, N))$q
-}
-
-lossdistC.jointZ <- function(dp, w, S, N, defaultflag = FALSE, rho, Z, wZ){
- ## N is the size of the grid
- ## dp is of size n.credits
- ## w is of size n.credits
- ## S is of size n.credits by nZ
- ## rho is a double
- ## Z is a vector of length nZ
- ## w is a vector if length wZ
- r <- .C("lossdistrib_joint_Z", as.double(dp), as.integer(length(dp)),
- as.double(w), as.double(S), as.integer(N), as.logical(defaultflag), as.double(rho),
- as.double(Z), as.double(wZ), as.integer(length(Z)), q = matrix(0, N, N))$q
-}
-
-lossdistC.prepay.jointblas <- function(dp, pp, w, S, N, defaultflag=FALSE){
- ## C version of lossdist.prepay.joint
- r <- .C("lossdistrib_prepay_joint_blas", as.double(dp), as.double(pp), as.integer(length(dp)),
- as.double(w), as.double(S), as.integer(N), as.logical(defaultflag), q=matrix(0, N, N))$q
- return(r)
-}
-
-lossdistC.prepay.jointZ <- function(dp, pp, w, S, N, defaultflag = FALSE, rho, Z, wZ){
- ## N is the size of the grid
- ## dp is of size n.credits
- ## pp is of size n.credits
- ## w is of size n.credits
- ## S is of size n.credits by nZ
- ## rho is a vector of doubles of size n.credits
- ## Z is a vector of length nZ
- ## w is a vector if length wZ
-
- r <- .C("lossdistrib_prepay_joint_Z", as.double(dp), as.double(pp), as.integer(length(dp)),
- as.double(w), as.double(S), as.integer(N), as.logical(defaultflag), as.double(rho),
- as.double(Z), as.double(wZ), as.integer(length(Z)), output = matrix(0,N,N))
- return(r$output)
-}
-
-lossrecovdist <- function(defaultprob, prepayprob, w, S, N, defaultflag=FALSE, useC=TRUE){
- lossdistrib2 <- if(useC) lossdistC
- recovdist <- if(useC) recovdistC
- if(missing(prepayprob)){
- L <- lossdistrib2(defaultprob, w, S, N, defaultflag)
- R <- lossdistrib2(defaultprob, w, 1-S, N)
- }else{
- L <- lossdistrib2(defaultprob+defaultflag*prepayprob, w, S, N, defaultflag)
- R <- recovdist(defaultprob, prepayprob, w, S, N)
- }
- return(list(L=L, R=R))
-}
-
-lossrecovdist.term <- function(defaultprob, prepayprob, w, S, N, defaultflag=FALSE, useC=TRUE){
- ## computes the loss and recovery distribution over time
- L <- array(0, dim=c(N, ncol(defaultprob)))
- R <- array(0, dim=c(N, ncol(defaultprob)))
- if(missing(prepayprob)){
- for(t in 1:ncol(defaultprob)){
- temp <- lossrecovdist(defaultprob[,t], , w, S[,t], N, defaultflag, useC)
- L[,t] <- temp$L
- R[,t] <- temp$R
- }
- }else{
- for(t in 1:ncol(defaultprob)){
- temp <- lossrecovdist(defaultprob[,t], prepayprob[,t], w, S[,t], N, defaultflag, useC)
- L[,t] <- temp$L
- R[,t] <- temp$R
- }
- }
- return(list(L=L, R=R))
-}
-
-lossrecovdist.joint.term <- function(defaultprob, prepayprob, w, S, N, defaultflag=FALSE, useC=TRUE){
- ## computes the joint loss and recovery distribution over time
- Q <- array(0, dim=c(ncol(defaultprob), N, N))
- lossdist.joint <- if(useC) lossdistC.jointblas
- lossdist.prepay.joint <- if(useC) lossdistC.prepay.jointblas
- if(missing(prepayprob)){
- for(t in 1:ncol(defaultprob)){
- Q[t,,] <- lossdist.joint(defaultprob[,t], w, S[,t], N, defaultflag)
- }
- }else{
- for(t in 1:ncol(defaultprob)){
- Q[t,,] <- lossdist.prepay.jointblas(defaultprob[,t], prepayprob[,t], w, S[,t], N, defaultflag)
- }
- }
- return(Q)
-}
-
-dist.transform <- function(dist.joint){
- ## compute the joint (D, R) distribution
- ## from the (L, R) distribution using D = L+R
- distDR <- array(0, dim=dim(dist.joint))
- Ngrid <- dim(dist.joint)[2]
- for(t in 1:dim(dist.joint)[1]){
- for(i in 1:Ngrid){
- for(j in 1:Ngrid){
- index <- i+j
- if(index <= Ngrid){
- distDR[t,index,j] <- distDR[t,index,j] + dist.joint[t,i,j]
- }else{
- distDR[t,Ngrid,j] <- distDR[t,Ngrid,j] +
- dist.joint[t,i,j]
- }
- }
- }
- distDR[t,,] <- distDR[t,,]/sum(distDR[t,,])
- }
- return( distDR )
-}
-
-shockprob <- function(p, rho, Z, log.p=F){
- ## computes the shocked default probability as a function of the copula factor
- ## function is vectorized provided the below caveats:
- ## p and rho are vectors of same length n, Z is a scalar, returns vector of length n
- ## p and rho are scalars, Z is a vector of length n, returns vector of length n
- if(length(p)==1){
- if(rho==1){
- return(Z<=qnorm(p))
- }else{
- return(pnorm((qnorm(p)-sqrt(rho)*Z)/sqrt(1-rho), log.p=log.p))
- }
- }else{
- result <- double(length(p))
- result[rho==1] <- Z<=qnorm(p[rho==1])
- result[rho<1] <- pnorm((qnorm(p[rho<1])-sqrt(rho[rho<1])*Z)/sqrt(1-rho[rho<1]), log.p=log.p)
- return( result )
- }
-}
-
-shockseverity <- function(S, Stilde=1, Z, rho, p){
- ## computes the severity as a function of the copula factor Z
- result <- double(length(S))
- result[p==0] <- 0
- result[p!=0] <- Stilde * exp( shockprob(S[p!=0]/Stilde*p[p!=0], rho[p!=0], Z, TRUE) -
- shockprob(p[p!=0], rho[p!=0], Z, TRUE))
- return(result)
-}
-
-dshockprob <- function(p,rho,Z){
- dnorm((qnorm(p)-sqrt(rho)*Z)/sqrt(1-rho))*dqnorm(p)/sqrt(1-rho)
-}
-
-dqnorm <- function(x){
- 1/dnorm(qnorm(x))
-}
-
-fit.prob <- function(Z, w, rho, p0){
- ## if the weights are not perfectly gaussian, find the probability p such
- ## E_w(shockprob(p, rho, Z)) = p0
- require(distr)
- if(p0==0){
- return(0)
- }
- if(rho == 1){
- distw <- DiscreteDistribution(Z, w)
- return(pnorm(q(distw)(p0)))
- }
- eps <- 1e-12
- dp <- (crossprod(shockprob(p0,rho,Z),w)-p0)/crossprod(dshockprob(p0,rho,Z),w)
- p <- p0
- while(abs(dp) > eps){
- dp <- (crossprod(shockprob(p,rho,Z),w)-p0)/crossprod(dshockprob(p,rho,Z),w)
- phi <- 1
- while ((p-phi*dp)<0 || (p-phi*dp)>1){
- phi <- 0.8*phi
- }
- p <- p - phi*dp
- }
- return(p)
-}
-
-fit.probC <- function(Z, w, rho, p0){
- r <- .C("fitprob", as.double(Z), as.double(w), as.integer(length(Z)),
- as.double(rho), as.double(p0), q = double(1))
- return(r$q)
-}
-
-stochasticrecov <- function(R, Rtilde, Z, w, rho, porig, pmod){
- ## if porig == 0 (probably matured asset) then return orginal recovery
- ## it shouldn't matter anyway since we never default that asset
- if(porig == 0){
- return(rep(R, length(Z)))
- }else{
- ptilde <- fit.prob(Z, w, rho, (1-R)/(1-Rtilde) * porig)
- return(abs(1-(1-Rtilde) * exp(shockprob(ptilde, rho, Z, TRUE) - shockprob(pmod, rho, Z, TRUE))))
- }
-}
-
-stochasticrecovC <- function(R, Rtilde, Z, w, rho, porig, pmod){
- r <- .C("stochasticrecov", as.double(R), as.double(Rtilde), as.double(Z),
- as.double(w), as.integer(length(Z)), as.double(rho), as.double(porig),
- as.double(pmod), q = double(length(Z)))
- return(r$q)
-}
-
-BClossdist <- function(defaultprob, issuerweights, recov, rho, Z, w,
- N=length(recov)+1, defaultflag=FALSE, n.int=500){
- if(missing(Z)){
- quadrature <- GHquad(n.int)
- Z <- quadrature$Z
- w <- quadrature$w
- }
- ## do not use if weights are not gaussian, results would be incorrect
- ## since shockseverity is invalid in that case (need to use stochasticrecov)
- LZ <- matrix(0, N, length(Z))
- RZ <- matrix(0, N, length(Z))
- L <- matrix(0, N, ncol(defaultprob))
- R <- matrix(0, N, ncol(defaultprob))
- for(t in 1:ncol(defaultprob)){
- for(i in 1:length(Z)){
- g.shocked <- shockprob(defaultprob[,t], rho, Z[i])
- S.shocked <- shockseverity(1-recov, 1, Z[i], rho, defaultprob[,t])
- temp <- lossrecovdist(g.shocked, , issuerweights, S.shocked, N)
- LZ[,i] <- temp$L
- RZ[,i] <- temp$R
- }
- L[,t] <- LZ%*%w
- R[,t] <- RZ%*%w
- }
- list(L=L, R=R)
-}
-
-BClossdistC <- function(defaultprob, issuerweights, recov, rho, Z, w,
- N=length(issuerweights)+1, defaultflag=FALSE){
- L <- matrix(0, N, dim(defaultprob)[2])
- R <- matrix(0, N, dim(defaultprob)[2])
- rho <- rep(rho, length(issuerweights))
- r <- .C("BCloss_recov_dist", defaultprob, dim(defaultprob)[1], dim(defaultprob)[2],
- as.double(issuerweights), as.double(recov), as.double(Z), as.double(w),
- as.integer(length(Z)), as.double(rho), as.integer(N), as.logical(defaultflag), L=L, R=R)
- return(list(L=r$L,R=r$R))
-}