docs: public static float[] makeMask(float sigma, int dim) {
          // 卷积核必须是奇数，才能有一个明显的中心核：
          // * * *
          // *[*]*
          // * * *
          dim |= 1; // 保证奇数矩阵
          float[] mask = new float[dim];
          float sigma2sq = 2 * sigma * sigma;
          float normalizeFactor = 1.0f / ((float) Math.sqrt(2.0 * Math.PI) * sigma);
  
          for (int i = 0; i < dim; i++) {
              int relPos = i - mask.length / 2;
              float G = (relPos * relPos) / sigma2sq;
              G = (float) Math.exp(-G);
              G *= normalizeFactor;
              mask[i] = G;
          }
          return mask;
      }