说明：  三种触摸屏或电磁屏校准算法的原理及源码，适用于你的触摸屏是只有线性变换的场合，比如旋转，缩放，偏移等这些线性变换。
(Principle and source of three touchscreen or electromagnetic screen calibration algorithm suitable for your touch screen is only a linear transformation of the occasion, such as rotation, scaling, offset, etc. These linear transformations.)