参数方程形式定积分 ∫ x 1 x 2 y d x ∫ x 1 x 2 y ( t ) d x ( t ) ∫ t 1 t 2 y ( t ) x ′ ( t ) d t , 其 中 x 1 x ( t 1 ) , x 2 x ( t 2 ) \int_{x_1}^{x_2} y \mathrm{d}x \int_{x_1}^{x_2} y(t) \mathrm{d}x(t) \int_{t_1}^{t_2} y(t)x(t)\mathrm{d}t, \\ 其中…
题意:JavaScript 中的正则表达式修饰符 /u 是什么? 问题背景:
Recently I have created a regex, for my PHP code which allows only the letters (including special characters plus spaces), but now Im having a problem with converti…