# ecmnhess

Hessian of negative log-likelihood function

## Description

example

Hessian = ecmnhess(Data,Covariance) computes an NUMPARAMS-by-NUMPARAMS Hessian matrix of the observed negative log-likelihood function based on current parameter estimates.

Use ecmnhess after estimating the mean and covariance of Data with ecmnmle.

example

Hessian = ecmnhess(___,InvCovar,MatrixType) adds optional arguments for InvCovar and MatrixType.

## Examples

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This example shows how to compute the Hessian for the negative log-likelihood function for five years of daily total return data for 12 computer technology stocks, with six hardware and six software companies

The time period for this data extends from April 19, 2000 to April 18, 2005. The sixth stock in Assets is Google (GOOG), which started trading on August 19, 2004. So, all returns before August 20, 2004 are missing and represented as NaNs. Also, Amazon (AMZN) had a few days with missing values scattered throughout the past five years.

[ECMMean, ECMCovar] = ecmnmle(Data)
ECMMean = 12×1

0.0008
0.0008
-0.0005
0.0002
0.0011
0.0038
-0.0003
-0.0000
-0.0003
-0.0000
⋮

ECMCovar = 12×12

0.0012    0.0005    0.0006    0.0005    0.0005    0.0003    0.0005    0.0003    0.0006    0.0003    0.0005    0.0006
0.0005    0.0024    0.0007    0.0006    0.0010    0.0004    0.0005    0.0003    0.0006    0.0004    0.0006    0.0012
0.0006    0.0007    0.0013    0.0007    0.0007    0.0003    0.0006    0.0004    0.0008    0.0005    0.0008    0.0008
0.0005    0.0006    0.0007    0.0009    0.0006    0.0002    0.0005    0.0003    0.0007    0.0004    0.0005    0.0007
0.0005    0.0010    0.0007    0.0006    0.0016    0.0006    0.0005    0.0003    0.0006    0.0004    0.0007    0.0011
0.0003    0.0004    0.0003    0.0002    0.0006    0.0022    0.0001    0.0002    0.0002    0.0001    0.0003    0.0016
0.0005    0.0005    0.0006    0.0005    0.0005    0.0001    0.0009    0.0003    0.0005    0.0004    0.0005    0.0006
0.0003    0.0003    0.0004    0.0003    0.0003    0.0002    0.0003    0.0005    0.0004    0.0003    0.0004    0.0004
0.0006    0.0006    0.0008    0.0007    0.0006    0.0002    0.0005    0.0004    0.0011    0.0005    0.0007    0.0007
0.0003    0.0004    0.0005    0.0004    0.0004    0.0001    0.0004    0.0003    0.0005    0.0006    0.0004    0.0005
⋮

To evaluate the negative log-likelihood function for ecmnmle, use ecmnhess based on the current maximum likelihood parameter estimates for ECMCovar.

Hessian = ecmnhess(Data,ECMCovar)
Hessian = 90×90
107 ×

0.0001    0.0000   -0.0000   -0.0000   -0.0000   -0.0000   -0.0000   -0.0000   -0.0000    0.0000   -0.0000   -0.0000         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
0.0000    0.0001   -0.0000   -0.0000   -0.0000    0.0000   -0.0000    0.0000   -0.0000   -0.0000    0.0000   -0.0000         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
-0.0000   -0.0000    0.0002   -0.0000   -0.0000   -0.0000   -0.0000   -0.0000   -0.0000   -0.0000   -0.0000   -0.0000         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
-0.0000   -0.0000   -0.0000    0.0003   -0.0000    0.0000   -0.0000   -0.0000   -0.0001   -0.0001   -0.0000   -0.0000         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
-0.0000   -0.0000   -0.0000   -0.0000    0.0001   -0.0000   -0.0000   -0.0000    0.0000   -0.0000   -0.0000   -0.0000         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
-0.0000    0.0000   -0.0000    0.0000   -0.0000    0.0000    0.0000   -0.0000    0.0000    0.0000    0.0000   -0.0000         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
-0.0000   -0.0000   -0.0000   -0.0000   -0.0000    0.0000    0.0002   -0.0000   -0.0000   -0.0000   -0.0000   -0.0000         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
-0.0000    0.0000   -0.0000   -0.0000   -0.0000   -0.0000   -0.0000    0.0004   -0.0000   -0.0000   -0.0000   -0.0000         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
-0.0000   -0.0000   -0.0000   -0.0001    0.0000    0.0000   -0.0000   -0.0000    0.0002   -0.0001   -0.0000   -0.0000         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
0.0000   -0.0000   -0.0000   -0.0001   -0.0000    0.0000   -0.0000   -0.0000   -0.0001    0.0004   -0.0000   -0.0000         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
⋮

## Input Arguments

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Data, specified as an NUMSAMPLES-by-NUMSERIES matrix with NUMSAMPLES samples of a NUMSERIES-dimensional random vector. Missing values are indicated by NaNs.

Data Types: double

Maximum likelihood parameter estimates for the covariance of the Data using the ECM algorithm, specified as a NUMSERIES-by-NUMSERIES matrix.

(Optional) Inverse of covariance matrix, specified as a matrix using inv as:

inv(Covariance)

Data Types: double

(Optional) Matrix format, specified as a character vector with a value of:

• 'full' — Computes the full Hessian matrix.

• 'meanonly' — Computes only the components of the Hessian matrix associated with the mean.

Data Types: char

## Output Arguments

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Hessian matrix, returned as an NUMPARAMSNUMPARAMS matrix of the observed log-likelihood function based on current parameter estimates, where NUMPARAMS = NUMSERIES * (NUMSERIES + 3)/2 if the MatrixFormat = 'full'. If the MatrixFormat = 'meanonly', then the NUMPARAMS = NUMSERIES.

## Version History

Introduced before R2006a