一阶偏微分方程完全积分概念的起源
贾小勇1,2,张小芳3
(1.西北大学数学与科学史研究中心,陕西西安710069;2.重庆文理学院数学与计算机科学系;3.重庆文理学院图书馆,重庆永川402160)
摘要:目的探讨和分析拉格朗日(Joseph L0uis Lagrange,1736-1813)重新定义一阶偏微分方程完 全积分概念的原因和背景。方法历史分析和文献考证。结果拉格朗日从欧拉的完全积分定义 出发,在用常数变易法探讨一阶偏微分方程积分的过程中受到启发,萌生了关于积分“完全性”的 新思想。随后,他把这种新思想运用于常微分方程,成功解释了奇解现象,受此驱动,提出了一阶偏 微分方程完全积分的新定义。结论拉格朗日的完全积分新定义是他追求方程一般性解法的体现 和产物。
关键词:拉格朗日(J0seph L0uis Lagrange,1736-1813);一阶偏微分方程;完全积分;常数变易 法;奇解
中图分类号:0211 文献标识码:A 文章编号:1000-274X(2007)04-0675-0
5
A study on the origin of the complete integral of
a first-order partial differential equation
JIA Xiao-yong1,2, ZHANG Xiao-fang3
(1. Research Center for the History of Mathematics and Science, Northwest University, Xi'an 710069, China;2. Mathematics and Com-
puter Science Department, .Chongqing University of Arts and Sciences;3. Library, Chongqing University of Arts and Sciences, Yong-
chuan 402160, China)
Abstract: Aim To explore the reasons why Lagrange redefined the concept of the complete integral of a first-order
partial differential equation. Methods Historic analysis and literature review. Results Lagrange hit upon the new
idea .to redefine the complete integral when he received the inspiration from his study on the first-order partial differ-
ential equation with the method of variation of constants. When he used this new idea to research the ordinary dif-
ferential equation, he .explained the singular integral successfully. Inspired by his method, Lagrange formally put forward his new concept of the complete integral Conclusion Lagrange's new definition showed his spirits of pur-
suing the general solution of the partial differential equation.
Key- words: Lagrange ( 1736-1813 ) ; first-order partial differential equation; complete integral; variation of con-
stants ;singular solution'