code: def _calculate_delta_input_variables(
      input_matrix: np.ndarray,
  ) -> np.ndarray:
      """Computes the delta values of the problem variables.
  
      For each point of the trajectory, computes how much each variable increased
      or decreased in respect to the previous point.
  
      Parameters
      ----------
      input_matrix: np.ndarray
          Matrix with the values of the problem's variables for all input points.
  
      Returns
      -------
      delta_variables: np.ndarray
          Variation of each variable, for each point in the trajectory.
      """
      delta_variables = np.subtract(
          input_matrix[:, 1:, :], input_matrix[:, 0:-1, :]
      )
  
      return delta_variables
  
imports: from typing import Dict, List
  import numpy
  from scipy.stats import norm
  from .None import common_args
  from ..util import read_param_file, compute_groups_matrix, ResultDict, _define_problem_with_groups, _compute_delta, _check_groups
label_desc: Use image node_id 8 for calling a global function with example usage: _calculate_delta_input_variables(input_matrix) and returns: delta_variables