Si函数维基百科,自由的 encyclopedia Si 函数定义如下[1][2] Si(x)的二维图像 S i ( z ) = ∫ 0 z sin ( t ) t d t {\displaystyle {\it {Si}}\left(z\right)=\int _{0}^{z}\!{\frac {\sin \left(t\right)}{t}}{dt}} S i ( z ) {\displaystyle Si(z)} 是下列三阶常微分方程的一个解: S i ( z ) = z d d z w ( z ) + 2 d 2 d z 2 w ( z ) + z d 3 d z 3 w ( z ) = 0 {\displaystyle {\it {Si}}\left(z\right)=z{\frac {d}{dz}}w\left(z\right)+2\,{\frac {d^{2}}{d{z}^{2}}}w\left(z\right)+z{\frac {d^{3}}{d{z}^{3}}}w\left(z\right)=0} 即: w ( z ) = _ C 1 + _ C 2 S i ( z ) + _ C 3 C i ( z ) {\displaystyle w\left(z\right)={\it {\_C1}}+{\it {\_C2}}\,{\it {Si}}\left(z\right)+{\it {\_C3}}\,{\it {Ci}}\left(z\right)}
Si 函数定义如下[1][2] Si(x)的二维图像 S i ( z ) = ∫ 0 z sin ( t ) t d t {\displaystyle {\it {Si}}\left(z\right)=\int _{0}^{z}\!{\frac {\sin \left(t\right)}{t}}{dt}} S i ( z ) {\displaystyle Si(z)} 是下列三阶常微分方程的一个解: S i ( z ) = z d d z w ( z ) + 2 d 2 d z 2 w ( z ) + z d 3 d z 3 w ( z ) = 0 {\displaystyle {\it {Si}}\left(z\right)=z{\frac {d}{dz}}w\left(z\right)+2\,{\frac {d^{2}}{d{z}^{2}}}w\left(z\right)+z{\frac {d^{3}}{d{z}^{3}}}w\left(z\right)=0} 即: w ( z ) = _ C 1 + _ C 2 S i ( z ) + _ C 3 C i ( z ) {\displaystyle w\left(z\right)={\it {\_C1}}+{\it {\_C2}}\,{\it {Si}}\left(z\right)+{\it {\_C3}}\,{\it {Ci}}\left(z\right)}