The method of endogenous gridpoints in theory and practice

The method of endogenous gridpoints (ENDG) significantly speeds up the solution to dynamic stochastic optimization problems with continuous state and control variables by avoiding repeated computations of expected outcomes while searching for optimal policy functions. I provide an interpolation technique for non-rectilinear grids that allow ENDG to be used in n-dimensional problems in an intuitive and computationally efficient way: the acceleration of ENDG with non-linear grid interpolation is nearly constant in the density of the grid. Further, ENDG has only been shown by example and has never been formally characterized. Using a theoretical framework for dynamic stochastic optimization problems, I formalize the method of endogenous gridpoints and present conditions for the class of models for which it can be used.     

The Impact of the Euro Changeover on Between-Currency Conversions

The present paper reviews available data about between-currency conversion strategies. Specifically, it compares conversion-strategy repertoires and execution before the euro changeover and 5.5 years thereafter. The data illuminate what between-currency conversion strategies people use, how they execute and select among them, why some strategies are favoured over other strategies, how long after the euro changeover people need to do conversions. These findings have important consequences for understanding how consumer behaviour may be facilitated by improving between-currency conversions, a key component for a successful currency changeover. This work was supported by grant from the Agence Nationale de la Recherche (Grant # 06-2-235061).     

Nominalising the numeric: an alternative to mathematical reduction in economics

Mathematical reduction in economics is the attempt to reducereasoning about human economic behaviour to the logic of numbersand numerical relations. The method of numerics shows how, insimple cases, the mathematical and non-mathematical componentsof economic theory can be both formally distinguished and integrated.However, in its compressed idiomatic form, this method treatsnumerics (the numerical terms in measuremental expressions)as determinatives (numerical adjectives) rather than as substantives.This paper shows how the numeric can be nominalised or giventhe grammatical status of a substantive. The method of numericsis then used to explore the fundamental flaws of mathematicalreduction in economists' efforts to achieve logical rigour inthe formalisation of economic theory.     

平面无误差直线轨迹控制系统

本文提出了一种平面无误差直线轨迹控制系统设计方案，用两轴进给速度控制达到数学原理的轨迹实现方法，并通过伺服控制实现无误差直线轨迹输出。这是一种适合于数控设备等两轴进给运动状态下的控制装置实现无误差加工的理想方法，其控制过程简便，理论误差为零。