code: # %%
  import torch
  import math
  from UnarySim.kernel.exp import expN1
  from UnarySim.stream.gen import RNG, SourceGen, BSGen
  from UnarySim.metric.metric import ProgError
  import matplotlib.pyplot as plt
  import time
  import math
  import numpy as np
  
  # %%
  def exp_comb_test(bw=8, mode="unipolar", rng="Sobol"):
      
      device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")
      total_cnt = 100
      bitwidth = bw
      btype = torch.float
      rtype=torch.float
      stype=torch.float
  
      print("========================================================")
      print(mode)
      print("========================================================")
      # all input values are non-negative
      low_bound = 0
      if mode == "unipolar":
          up_bound = 2**bitwidth
      elif mode == "bipolar":
          low_bound = 0
          up_bound = 2**(bitwidth-1)
  
      input_list = []
      for input_val in range(low_bound, up_bound+1, 1):
          input_list.append(input_val)
  
      input = torch.tensor(input_list).type(torch.float).div(up_bound).to(device)
      output = torch.exp(input.mul(-1))
      
      result_pe_total = []
      for rand_idx in range(1, total_cnt+1):
          
          outputPE = ProgError(output, mode=mode).to(device)
          inputPE  = ProgError(input,  mode=mode).to(device)
          
          dut_exp_comb = expN1(mode=mode, 
                               rng=rng, 
                               rng_dim=rand_idx, 
                               rng_width=bitwidth).to(device)
          inputSRC = SourceGen(input, bitwidth, mode=mode, rtype=rtype)().to(device)
          inputRNG = RNG(bitwidth, rand_idx, rng, rtype)().to(device)
          inputBS = BSGen(inputSRC, inputRNG, stype).to(device)
          with torch.no_grad():
              start_time = time.time()
              for i in range(2**bitwidth):
                  input_bs = inputBS(torch.tensor([i]))
                  inputPE.Monitor(input_bs)
  
                  output_bs = dut_exp_comb(input_bs)
                  outputPE.Monitor(output_bs)
          
          # get the result for different rng
          result_pe = outputPE()[1].cpu().numpy()
          result_pe_total.append(result_pe)        
      
      # get the result for different rng
      result_pe_total = np.array(result_pe_total)
      #######################################################################
      # check the error of all simulation
      #######################################################################
      print("RMSE:{:1.4}".format(math.sqrt(np.mean(result_pe_total**2))))
      print("MAE: {:1.4}".format(np.mean(np.abs(result_pe_total))))
      print("bias:{:1.4}".format(np.mean(result_pe_total)))
      print("max: {:1.4}".format(np.max(result_pe_total)))
      print("min: {:1.4}".format(np.min(result_pe_total)))
  
      #######################################################################
      # check the error according to input value
      #######################################################################
      max_total = np.max(result_pe_total, axis=0)
      min_total = np.min(result_pe_total, axis=0)
      avg_total = np.mean(result_pe_total, axis=0)
      
      axis_len = outputPE()[1].size()[0]
      input_x_axis = []
      for axis_index in range(axis_len):
          input_x_axis.append((axis_index/(axis_len-1)*(up_bound-low_bound)+low_bound)/up_bound)
      fig, ax = plt.subplots()
      ax.fill_between(input_x_axis, max_total, avg_total, facecolor="red", alpha=0.75)
      ax.fill_between(input_x_axis, avg_total, min_total, facecolor="blue", alpha=0.75)
      ax.plot(input_x_axis, avg_total, label='Avg error', color="black", linewidth=0.3)
      plt.tight_layout()
      plt.xlabel('Input value')
      plt.ylabel('Output error')
      plt.xticks(np.arange(0, 1.1, step=0.5))
      # ax.xaxis.set_ticklabels([])
      plt.xlim(0, 1)
      plt.yticks(np.arange(-0.2, 0.4, step=0.2))
      # ax.yaxis.set_ticklabels([])
      plt.ylim(-0.3, 0.55)
      plt.grid(b=True, which="both", axis="y", linestyle="--", color="grey", linewidth=0.3)
      fig.set_size_inches(4, 4)
      ax.spines['right'].set_visible(False)
      ax.spines['top'].set_visible(False)
      plt.show()
      plt.close()
  
  # %%
  exp_comb_test(8,"unipolar", "Sobol")
  
  # %%
  exp_comb_test(8, "unipolar", "SYS")
  
  # %%
  exp_comb_test(8, "unipolar", "LFSR")
apis: matplotlib.pyplot.grid matplotlib.pyplot.tight_layout torch.no_grad numpy.abs torch.tensor matplotlib.pyplot.subplots matplotlib.pyplot.xlim numpy.arange numpy.max matplotlib.pyplot.ylabel numpy.min matplotlib.pyplot.ylim matplotlib.pyplot.show numpy.array matplotlib.pyplot.close torch.cuda.is_available matplotlib.pyplot.xlabel numpy.mean