Several questions regarding construction of functions
摘要：
1. Does there exist function $f$ such that: 1) $f\in C_0^\infty(\mathbf{R}^n)$, $f$ is supported in $\{x:|x|\leq 2\}$; 2) $f(x)\equiv 1$, if $|x|\leq 1$; 3) $f(x)\geq 0, \, \hat f(\xi)\geq 0$.2. Does there exist function $f$ such that: 1) $f\in C_0^\infty(\mathbf{R}^n)$, $f$ is supported in $\{x:1/2 阅读全文
posted @ 2013-03-15 13:19 Zihua 阅读(173) 评论(0) 推荐(0) 编辑
