def rms_p(n):
""" INPUT: nth energy level
OUTPUT: value of the root-mean-square momentum(p) """
def rms_pintegrand(z):
def x(z):
return z / (1 - z)
if n == 0:
return (np.abs(
(1 / np.sqrt(2**n * math.factorial(n) * np.sqrt(np.pi))) *
np.e**(-x(z)**2 / 2) *
(-x(z) * h(0, x(z)) + 2 * n * h(0, x(z))))
)**2 #integrand of <p> for n=0
elif n == 1:
return (np.abs(
(1 / np.sqrt(2**n * math.factorial(n) * np.sqrt(np.pi))) *
np.e**(-x(z)**2 / 2) *
(-x(z) * h(1, x(z)) + 2 * n * h(1, x(z))))
)**2 #integrand of <p> for n=1
else:
return (np.abs(
(1 / np.sqrt(2**n * math.factorial(n) * np.sqrt(np.pi))) *
np.e**(-x(z)**2 / 2) * (-x(z) * h(n, x(z)) + 2 * n * h(
(n - 1), x(z)))))**2 #integrand of <p> for n>2
#integral of uncertainty of momentum
I = 0.0
N = 100
a = 0
b = 1
x, w = gaussxwab(N, a, b)
for k in range(N):
I += w[k] * rms_pintegrand(x[k])
return np.sqrt(2 * I)
def prob_blowing_snow(u10, Ta, th, N):
"""
Function that uses gaussian quadrature to calculate
the probability of blowing snow
Parameters
----------
u10 : float
Average hourly windspeed at 10m.
Ta : float
Average hourly temperature
th : float
Snow surface age.
N : int
Number of sample points.
Returns
-------
float
Probability of blowing snow in these conditions.
"""
# Mean and standard deviation wind speed
ubar = 11.2 + 0.365*Ta + 0.00706*Ta**2 + 0.9*np.log(th)
delta = 4.3 + 0.145*Ta + 0.00196*Ta**2
# Integrand as a function u, wind speed
integrand = lambda u : np.exp(-(ubar-u)**2/(2*delta**2))
# Calculation of integral using gaussian quadrature
s, w = gaussxwab(N, 0, u10)
integral = np.sum(w*integrand(s))
# Normalize integral to calculate probability
return integral/(np.sqrt(2*np.pi)*delta)
def quad(a, b, f, n):
x, w = gaussxwab(n, a, b)
integral = []
for i in range(n):
integral.append(w[i] * f(x[i]))
resultado = sum(integral)
return resultado
def int_gauss(f, a, b, N, error=0.0):
k = np.arange(N)
s, w = gaussxwab(N, a, b)
result = f(s[k])
while w.ndim != result.ndim:
w = w[:, None]
return np.nansum((w * result), axis=0)
def gaussian_quadrature(f, a, b, n):
"""
Integrate the function f from a to b using gaussian quadrature
with n slices.
Code is based on example on p.170 in the textbook.
Parameters
----------
f : (float -> float)
1-D continuous function.
a : float
Lower limit of integration.
b : float
Upper limit of integration.
n : int
Number of slices.
Returns
-------
Approximate value of f integrated from a to b.
"""
x, w = gaussxwab(n, a, b)
return np.sum([w[i] * f(x[i]) for i in range(n)])
def gauss_quad(func, x_min, x_max, N=1000, **kwargs):
"""
Gaussian quadrature method to integrate a function between two given limits.
Parameters
------------
func : function
Function to be integrated.
x_min : scalar
Lower limit of integration.
x_max : scalar
Upper limit of integration.
N : int,optional
Number of points for quadrature method.
**kwargs :
Extra arguments for the integrand function func.
Returns
---------
value : scalar
Integration value.
"""
xp, wp = gaussxwab(N, x_min, x_max)
y = func(xp, **kwargs)
int_value = sum(wp * y)
return int_value
def integrateG(f,n,a,b,N): x,w = gaussxwab(N,a,b) xp = 0.5*(b-a)*x +0.5*(b+a) wp = 0.5*(b-a)*w s=0 for k in range (N): s+= wp[k]*f(xp[k],n) return s
def cv(Temp):
# do __sum__
TEMP = Temp / debeye
__sum__ = 0.0
x,w = gaussxwab(50,0,1/TEMP)
for k in range(50):
__sum__ += w[k] * f(x[k])
return __sum__ * cv_0 * (TEMP**3)
def normalizeAndGraph(E):
n = 100
x,w = gaussxwab(n,-L/2,0)
s = 0
for i in range(n):
ds = ((hbar**2)/2*m*(V(x[i]-E)))**2
s += w[i]*ds
phi = 0.5/sqrt(s)
solve(E, phi, 1)
def dawson_gauss(x, N):
a = 0.0
b = x
s, w = gaussxwab(N + 1, a, b)
coeff = np.exp(-x**2)
integral = dawson_integral(s, w)
return coeff * integral
def gamma(func2, C):
N = 200
a = 0.0
b = 1.0
x, w = gaussxwab(N, a, b)
s = 0.0
for k in range(N):
s += w[k] * func2(C, x[k])
return s
def expect_p2(n, p):
#function to be integrated over
def func(x):
return ((1+x**2)/((1-x**2)**2))*(np.abs(wavefunc_derivative(n,(x/(1-x**2)))))**2
N,a,b = p
x,w = gaussxwab(N,a,b)
I = 0.0
for i in range(N):
I += w[i]*func(x[i])
return I
def gaussint(fn,Nsamp,lowlim,uplim,args = False): """ Returns the integral of fn from lowlim to uplim using Gaussian quadrature with Nsamp sample points. """ x,w = gaussxwab(Nsamp,lowlim,uplim) # gets points and weights s = np.zeros(np.shape(args)) for i in range(Nsamp): s += w[i]*fn(x[i],args) # evaluate fn at points and weight it return s
def Efficiency(l1, l2, T, N, f):
"""
This function uses Gaussian Quadrature method to calculate the integrals
needed for the efficiency given the bounds of wavelengths.
"""
x, w = gaussxwab(N, l1, l2)
results = 0
for i in range(N):
results += w[i] * f(x[i], T)
return results
def gaussint(fn, Nsamp, lowlim, uplim, args=False):
"""
Returns the integral of fn from lowlim to uplim using Gaussian
quadrature with Nsamp sample points.
"""
x, w = gaussxwab(Nsamp, lowlim, uplim) # gets points and weights
s = np.zeros(np.shape(args))
for i in range(Nsamp):
s += w[i] * fn(x[i], args) # evaluate fn at points and weight it
return s
def dbasis_quad(curve, N, i, j, k, t, d):
"""
For E norms:
Multiply 2 Derivative Basis Functions and Integrate
Modified to use correct starting and end vertices for these product basis
functions.
N = order of accuracy of the integration - should match the order of the new D
basis Dbasis function
i = the ith function in the Mij matrix
j = the jth function im the Mij matrix
p = degree (actually passing order) of the curve
t = knot vector
d = derivative order
"""
p = curve.p
## ESTABLISH THE LIMITS OF INTEGRATION:
## a=min, b=max
ij_min = max(i, j) #could use this always assuming assending knot order...
ij_max = min(k + i, k + j)
#Now we need to divide the span into continuous segments, if not already continuous...
rel_knot_set = list(set(
t[ij_min:ij_max +
1])) # oh boy... am I intoducing something weird here?
rel_knot_set = sorted(rel_knot_set) #cruical!
# Calculate the sample vertices and weights, then map them
# to the required integration domain
s = 0.0
if (len(rel_knot_set) < 2):
pass
else:
for ii in range(len(rel_knot_set) - 1):
a = rel_knot_set[ii]
b = rel_knot_set[ii + 1]
x, w = gaussxwab(N, a, b)
"""
returns integration points, x
and
integration weights, w
mapped to the integral of a to b
"""
# Perform the integration
b1 = np.zeros((curve.n, curve.n), float)
for pt in range(N):
b1[:, :] = 0.0
span = curve.FindSpan(x[pt])
curve.DersBasisFunc(span, x[pt], b1[:, span - p:span + 1])
s += w[pt] * b1[d, i] * b1[d, j] #sum over all N
return s
def eta(T):
def f(x):
return x**3/(np.exp(x)-1)
#Quadratura gaussiana com N = 100 usando a gaussiana do mark newman.
N=100
x,w=gaussxwab(N,Inferior/T,Superior/T)
integral=0.0
for k in range(N):
integral+=w[k]*f(x[k])
return 15/np.pi**4*integral
def gaussint(fn,Nsamp,lowlim,uplim): """ Returns the integral of fn from lowlim to uplim using Gaussian quadrature with Nsamp sample points. """ x,w = gaussxwab(Nsamp,lowlim,uplim) # gets points and weights s = 0.0 # start sum at zero for i in range(Nsamp): s += w[i]*fn(x[i]) # evaluate fn at points and weight it return s
def gauss_q_integral_calc(N, n, a, b, f):
"""
N: number of sample points.
a,b: interval lef and right boundary.
f: the function we want its integral.
*Inspired from the Textbook.
"""
x, w = gaussxwab(N, a, b)
s = 0.0
for j in range(N):
s += (w[j] * f(x[j], n))
return s
def quad(a, b, n):
I2 = []
resultado = []
theta, w = gaussxwab(n, a, b)
for m in range(3):
for x in X:
for i in range(n):
I2.append(float(w[i] * f(theta[i], m, x)))
resultado.append(float(sum(I2)))
I2 = []
RES2.append(resultado)
resultado = []
def eta(T):
def f(x):
return x ** 3 / (exp(x) - 1)
# We use Gaussian quadrature with N = 100 sample points
N = 100
x, w = gaussxwab(N, lower_constant / T, upper_constant / T)
integral = 0.0
for k in range(N):
integral += w[k] * f(x[k])
return 15 / pi ** 4 * integral
def gaussian(f, a, b, n=n):
# removes ambiguity error with gauss method
f = g
x, w = gaussxwab(n, a, b)
# while(error > accuracy):
# n = n*2
# x, w = gaussxwab(n, a, b)
# print(n)
# print(error)
return sum(f(x) * w)
def finite_integration(f, frm=0.0, to=pi, method='simpson', N=60):
"""Calculates finite integration of a function (f) inside given interval
by either Simpson method or Gaussian quadrature
Positional arguments:
f -- function to integrate (type function)
Keyword arguments:
frm -- lower bound of integration (default 0.0)
to -- upper bound of integration (default pi)
method -- method of numeric integration to run [options 'simpson',
'gauss'] (default 'gauss')
n -- number of samples to use (defualt 60)
"""
# Simpson method case
if method == 'simpson':
terms = [] # to feed with simpsons formula sum terms
delta_x = (to - frm) / N
# 1st term caculation
terms.append(delta_x * (f(frm) + f(to)) / 3)
# 2nd term caculation
s, k = 0.0, 1
while k <= N - 1:
s += f(frm + k * delta_x)
k += 2
terms.append(4 * delta_x * s / 3)
# 3rd term caculation
s, k = 0.0, 2
while k <= N - 2:
s += f(frm + k * delta_x)
k += 2
terms.append(2 * delta_x * s / 3)
return sum(terms)
# Gaussian quadrature case
if method == 'gauss':
from gaussxw import gaussxwab
# Calculates os samples nd weights inside [frm, to] interval
x, w = gaussxwab(N, frm, to)
# Does summation
s = 0.0
for k in range(N):
s += w[k] * f(x[k])
return s
def T(a):
def f(x):
def v(y):
return y**4
return 1 / sqrt(v(a) - v(x))
x, w = gaussxwab(n_points, 0, a)
integral = 0.0
for k in range(n_points):
integral += w[k] * f(x[k])
return sqrt(8) * integral
def T(a):
def f(x):
def v(y):
return y**4
return 1 / np.sqrt(v(a) - v(x))
x, w = gaussxwab(N, 0, a)
integral = 0.0
for k in range(N):
integral += w[k] * f(x[k])
return np.sqrt(8) * integral
def Efficiency(l1, l2, T, N):
"""
This function takes blah blah blah
"""
#transform
a = 1 - 1 / l1
b = 1 - 1 / l2
#Gaussian Quadrature
x, w = gaussxwab(N, a, b)
results = 0
for i in range(N):
results += w[i] * I(x[i], T)
return results
def gaussint(fn, Nsamp, lowlim, uplim, args=False):
"""
Returns the integral of fn from lowlim to uplim using Gaussian
quadrature with Nsamp sample points.
"""
x, w = gaussxwab(Nsamp, lowlim, uplim) # gets points and weights
s = 0.0 # start sum at zero
for i in range(Nsamp):
if args == False:
s += w[i] * fn(x[i]) # evaluate fn at points and weight it
elif args != False:
s += w[i] * fn(x[i], args) # evaluate fn at points and weight it
return s
def integrator(f, a, b, N):
"""
integrates f from a to b using Gaussian quadrature with N points, requires gaussxwab
:param f: 1d function
:param a: lower bound of domain
:param b: upper bound of domain
:param N: number of points
:return: floating value of integral
"""
x, w = gaussxwab(N, a, b)
integral = 0.0
for k in range(N):
integral += w[k] * f(x[k])
return integral
def c_v(T):
c = 7.48279 # = 9V * rho * k_B in SI units
theta_d = 428 # in K
def f(x):
return x**4 * exp(x) / (exp(x) - 1)**2
# perform the integration using Gaussian quadrature
n_points = 50
x, w = gaussxwab(n_points, 0, theta_d / T)
integral = 0.0
for k in range(n_points):
integral += w[k] * f(x[k])
return c * (T / theta_d)**3 * integral
def integrateBlackBodyComponent(x):
# Calculate upperbound to use as minimum iteration.
upperBoundX = np.log(1_000_000_000)
# Assuming previous integral evaluating from 0 to 2 with 1000 (excessive) iterations.
a = 0
b = np.ceil(upperBoundX)*20 # Multiply to exceed upperbound even further.
N = 1000
# Calculate weights and integration points and sum.
integrationPoints, weights = gaussxw.gaussxwab(N , a, b)
result = (np.array(weights * f(integrationPoints))).sum()
return result # ~6.4939394022668291
def n(T):
k = 1.38065e-23 # joules/kelvin
c = 3e8 # meters/second
N = 100
a = h*c/(lam2*k*T)
b = h*c/(lam1*k*T)
x,w = gaussxwab(N,a,b)
s = 0.0
for k in range(N):
s += w[k]*(x[k]**3/(exp(x[k])-1))
s = s*(15/(pi*pi*pi*pi))
return s
def gauss_int(N, func1, func2):
"""
Testing simple functions
using gaussian integration:
N = order of accuracy of the integration - should match the order of the new D
basis Dbasis function, or be higher - this shouldn't hurt but should
be slower
func1 = a function
func2 = a function
"""
#itegration interval
a = 0.
b = 1.
# Calculate the sample vertices and weights, then map them
# to the required integration domain
#x,w = gaussxw(N)
x, w = gaussxwab(N, a, b)
#print 'x = {}'.format(x)
#print 'w = {}'.format(w)
"""
input:
N =
a = min
b = max
returns integration vertices, x
and
integration weights, w
mapped to the integral of a to b
"""
# these are only used if you use the naive algorithm "gaussxw(N)"
#xp = 0.5*(b-a)*x + 0.5*(b+a)
#wp = 0.5*(b-a)*w
#print 'x = {}; w = {}'.format(x,w)
# Perform the integration
s = 0.0
for k in range(N):
s += w[k] * func1(x[k]) * func2(x[k])
#print 'k={}; x[{}] = {}, w[{}]={}'.format(k,k,x[k],k,w[k])
#print 's={}'.format(s)
#print 'for k = N={}, Final s={}'.format(k, s)
return s
def rms_x(n):
""" INPUT: nth energy level
OUTPUT: value of the root-mean-square position(x) """
def rms_xintegrand(z):
def x(z):
return z / (1 - z) #change of variables: equation 5.67
return x(z)**2 * np.abs(psi(n, x(z)))**2 * (1 / (1 - z)**2
) #integrand of <x>
#integral of uncertainty of position
I = 0.0
N = 100
a = 0
b = 1
x, w = gaussxwab(N, a, b)
for k in range(N):
I += w[k] * rms_xintegrand(x[k])
return np.sqrt(2 * I)
from gaussxw import gaussxwab
from math import exp
def f(z):
return exp(-z**2/(1-z)**2)/(1-z)**2
N = 50
a = 0.0
b = 1.0
x,w = gaussxwab(N,a,b)
s = 0.0
for k in range(N):
s += w[k]*f(x[k])
print(s)
# author: jiinso
# In Class Exercise 9
# 2014/9/30
# Gaussian Quadrature Integration
# Import the function gaussxwab from the module gaussxw
from gaussxw import gaussxwab
# Define the function to be integrated.
def f(x):
return x**4 - 2*x + 1
# Set the N values and limits of integration a and b
# Note that the function guassxwab only integrates upto the N values 1000: do NOT set N higher than 1000.
N = 1000
a = 0
b = 2
# Call on the function gaussxwab to obtain x and c values.
x1, c1 = gaussxwab(N, a, b)
# Do a summation of the c(x1)* f(x1) for each number in range N.
S = 0.0
for i in range(N):
S += c1[i] * f(x1[i])
# Print the summation out.
print ('The Gaussian Quadrature integration of this function is %2.20f. ' %S)
from gaussxw import gaussxwab
import matplotlib.pyplot as plt
###############################################################################
# This code animates the temperature in a cylinder as a function of radius over
# time.
################################## CONSTANTS ##################################
Nint = 100 # Number of subintervals for Gaussian integration
b = np.pi # Upper bound of Bessel function integral
a = 0 # Lower bound of Bessel function integral
# Generate points and weights for Gaussian integration
taus,weights = gaussxwab(Nint,a,b)
# Set parameters for the cylinder
R = 10. # Radius of the cylinder
T0 = 50. # Initial temperature of the cylinder
c = 1.25 # Speed at which heat change propagates through the cylinder
################################## FUNCTIONS ##################################
def gaussint(fn,tau,w,args = False):
"""
Returns the integral of fn from lowlim to uplim using Gaussian
quadrature with Nsamp sample points.
"""
s = np.zeros(np.shape(args))
for i in range(len(tau)):
import numpy as np
from scipy.special import jn_zeros
from gaussxw import gaussxwab
N = 100
b = np.pi
a = 0
taus,weights = gaussxwab(N,b,a)
def gaussint(fn,x,w,args = False):
"""
Returns the integral of fn from lowlim to uplim using Gaussian
quadrature with Nsamp sample points.
"""
s = np.zeros(np.shape(args))
for i in range(len(x)):
s += w[i]*fn(x[i],args) # evaluate fn at points and weight it
return s
def J0int(tau,x):
return np.cos(x*np.sin(tau))
def J0(x):
return (1./np.pi)*gaussint(J0int,taus,weights,args = x)
def secant(initial,fn,tol):
x1,x2 = initial
while True:
# Find slope of secant line connecting x1 and x2
fprime = (fn(x2) - fn(x1))/(x2-x1)
# Rebecca Li
# In class exercise
from gaussxw import gaussxwab
#define the function we are going to integrate
def f(x):
return x**4-2*x+1
N = 13 # N-th order Gaussian intergration
a = 0 # Starting point
b = 2 # Ending point
x,w = gaussxwab(N,a,b) # Use the function gaussxwab to get the integration
# point x and its weight mapped to the interval [a,b]
I = 0 # Set the initial integral as 0
for i in range(N): # Integrate
I += f(x[i])*w[i]
print 'The intergral is %5.17f' %I