#!/usr/bin/env python # coding: utf-8 # # Problem 1 # Integrate the following equation using the Trapazoid Rule, Simpson's rule, and Gauss-Legendre quadrature from x=0 to x=1: # # $$f(x) = x\cdot\tanh(d\cdot(x-0.5))+1.$$ # # Use d=10. Make a log-log plot of the relative error of the methods versus the number of grid points. To get the "exact" integral, you can use the built-in integrator. # # In python, use the following: # # from scipy.integrate import quad # (Ie, abserr) = quad(f,0,1) # # When varying the number of points, because we are plotting on a log scale, and because the error goes as a power, we want the number of points to increase as a power. I did something like: # # npoints = 2^1, 2^2, 2^3, 2^4, 2^5, 2^6, 2^7, 2^8, 2^9, 2^10, # # for 10 runs. Then, when you plot on a log scale you'll have an even spacing of points on the x-axis. # # Use your results to verify that the trapazoid and Simpson methods have convergence rates $O(\Delta x^2)$ and $O(\Delta x^4)$, respectively. # In[1]: get_ipython().run_line_magic('matplotlib', 'inline') import matplotlib.pyplot as plt import numpy as np from scipy.integrate import quad # ## Problem 2 # This problem is from Hoffman's book: Chapter 4 problem 106 (b). # # The following temperature and rate data were measured: # # | T(K) | K$_f$ | # |:----:|:-----:| # |1000 | 7.5E15| # |2000 | 3.8E15| # |3000 | 2.5E15| # |4000 | 1.9E15| # |5000 | 1.5E15| # # Find parameters $B$, $\alpha$, and $E/R$ for the model # # $$K = BT^{\alpha}\exp\left(-\frac{E}{RT}\right).$$ # # Plot the model with the best coefficients with a smooth line (use lots of T points). Also plot the measured points using data markers (not lines). # In[ ]: # ## Problem 3 # Evaluate the function $f(x)=\exp(4x)$ at $x=0.55$ using a cubic spline fit to points $x=0,\,0.2,\,0.4,\,0.8,\,1.0.$ Also report the relative error at $x=0.55$. (Code the spline yourself.) # In[ ]: