## 2D Histogram Operations

Function: int gsl_histogram2d_equal_bins_p (const gsl_histogram2d *h1, const gsl_histogram2d *h2)
  This function returns 1 if the all of the individual bin ranges of the two histograms are identical, and 0 otherwise.

Function: int gsl_histogram2d_add (gsl_histogram2d *h1, const gsl_histogram2d *h2)
  This function adds the contents of the bins in histogram h2 to the corresponding bins of histogram h1, i.e. h'_1(i,j) = h_1(i,j) + h_2(i,j). The two histograms must have identical bin ranges.

Function: int gsl_histogram2d_sub (gsl_histogram2d *h1, const gsl_histogram2d *h2)
  This function subtracts the contents of the bins in histogram h2 from the corresponding bins of histogram h1, i.e. h'_1(i,j) = h_1(i,j) - h_2(i,j). The two histograms must have identical bin ranges.

Function: int gsl_histogram2d_mul (gsl_histogram2d *h1, const gsl_histogram2d *h2)
  This function multiplies the contents of the bins of histogram h1 by the contents of the corresponding bins in histogram h2, i.e. h'_1(i,j) = h_1(i,j) * h_2(i,j). The two histograms must have identical bin ranges.

Function: int gsl_histogram2d_div (gsl_histogram2d *h1, const gsl_histogram2d *h2)
  This function divides the contents of the bins of histogram h1 by the contents of the corresponding bins in histogram h2, i.e. h'_1(i,j) = h_1(i,j) / h_2(i,j). The two histograms must have identical bin ranges.

Function: int gsl_histogram2d_scale (gsl_histogram2d *h, double scale)
  This function multiplies the contents of the bins of histogram h by the constant scale, i.e. h'_1(i,j) = h_1(i,j) scale.

Function: int gsl_histogram2d_shift (gsl_histogram2d *h, double offset)
  This function shifts the contents of the bins of histogram h by the constant offset, i.e. h'_1(i,j) = h_1(i,j) + offset.