FFT源码，快速傅里叶变换和逆变换，Portable ISO C++开发的完整类-FFTReal Version 1.03, 2001/06/15 Class of Fourier transformation of real data (FFT and IFFT) Portable ISO C++ (c) Laurent de Soras <ldesoras@club-internet.fr>

绝缘阻抗检测，当方阵的接地绝缘阻抗过低的时候，逆变器无法并网，会报ISO错误-Insulation resistance detection

异面相交直线公垂线中点坐标值求解。可用于计算并联机构U关节的坐标值。-Iso-surface well intersecting lines perpendicular to solve midpoint coordinate values. Parallel mechanism can be used to calculate the U joint coordinates.

isotropic hardening umat