Strong Taylor Schemes for Stochastic Volatility
Ito and Stratonovich Stochastic Calculus
Ito-Stratonovich drift conversion
Strong Numerical Schemes for SDE
Milstein scheme for commutative noise
Approximations of Volatility Models
General 2D Milstein scheme for stochastic volatility models
Approximations of the Double Integral
Subdivision (Kloeden - IC = 0)
Simulation of the Double Integral
Formulae derivation for Heston Volatility
Derivation of the 2D Milstein Scheme
Certain structural relationships between the noise coefficient vectors bj,j of an SDE that are known as commutative noise allow considerable simplifications to numerical schemes, in particular, the avoidance of the need to simulate multiple stochastic integrals. The {SDE-3} is said to have commutative noise (of the first kind) when:
![]()
for: i = 1, ..., N ; j1, j2 = 1, ..., M
Then the identities {11} for j1, j2 = 1, ..., M with j1 ≠ j2 can be used to simplify the Milstein scheme to give:
(12)
which is called the Milstein scheme for commutative noise.
Order 1.5 strong stochastic Taylor scheme
The i th component of the order 1.5 strong Taylor scheme for the Ito {SDE- 3} is given by:
(13)
for i = 1, ..., N, where I(j1,j2,j3);n is the multiple Ito integral:

with the special case:

Also
![]()
where the random variable
![]()
distributed and has covariance
![]()
Order 2.0 strong stochastic Taylor scheme
The order 2.0 strong Taylor scheme for the N-dimensional Stratonovich {SDE-5} with an M-dimensional Wiener process:

f or i = 1, ..., N ; j = 1, ..., M
is given by:
(14)
for i = 1, ..., N. The J(j1,j2);n, J(j1,j2,j3);n and J(j1,j2,j3,j4);n expressions here denote the corresponding Stratonovich integrals with respect to the components of the given Wiener process.
Prof. Klaus Schmitz

Strong Taylor Schemes for Stochastic Volatility
This method requires formulas that are not always easy or possible to find. In this document, we present the corresponding approximations for both Euler and Milstein schemes for the usual Geometric Brownian Motion and the stochastic volatility models. Also, we present five methods of how we can simulate the double integrals for the 2 dimensional Milstein approximation.
By Prof. Klaus Erich Schmitz Abe