This script runs automatically. If loaded to your calculator you not import it to your shell automatically.

Calculates a Leftriemannsum of a set of points. First input your x-values in a list Example: 1,2,3,4 Then input your y-values in a list Example: 1,4,9,16

See sum, and graph.

from math import *
from cmath import *
from matplotlib.pyplot import *

# --- Input Phase ---
print("Separated using commas")
print("Enter x-values:")
x_vals = [float(i) for i in input().split(",")]

print("Enter y-values:")
y_vals = [float(i) for i in input().split(",")]

n = len(x_vals)
if len(y_vals) != n:
    print("Error: x and y must have same length")
else:
    # --- Compute Left Riemann Sum ---
    total = 0
    for i in range(n-1):
        width = x_vals[i+1] - x_vals[i]
        total += y_vals[i] * width

    print("Left Riemann Sum =", total)

    # --- Wait before plotting ---
    input("Press Enter to see graph...")

    # --- Plotting ---
    x_min = int(min(x_vals)-2)
    x_max = int(max(x_vals)+2)
    y_min = int(min(y_vals)-2)
    y_max = int(max(y_vals)+2)
    
    # Plot the (x,y) points
    axis((x_min,x_max,y_min,y_max))

    # Draw left Riemann sum rectangles
    for i in range(n-1):
        width = x_vals[i+1]-x_vals[i]
        bar(x_vals[i]+width/2, y_vals[i], width)
    text(x_min+0.5,y_max-0.5,"LR="+str(round(total,2)))
    plot(x_vals, y_vals, color='red',zorder=2)

    show()