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Informatique Introduction à Scipy Python scientifique Scipy

scipy.fftpack transformation de Fourier scipy.integrate intégration et intégration d'équations différentielles scipy.interpolate interpolation scipy.linalg.



Introduction à Numpy et Scipy

import numpy as np. # Ces deux là amènent aussi un certain. 2 import scipy as sp. # nombre de fonctions mathématiques. 3 import scipy.integrate.



Mathématiques et Python

En effet nombre de fonctions ainsi que le type 'ndarray' de Scipy sont en fait ceux définis dans Numpy. 2.3.1 Intégration numérique. Scipy propose une série de 



scipy : librairie pour la programmation scientifique

Algorithmes d'interpolation d'intégration et d'optimisation. ? Traitement du signal et des images (transformée de Fourier



Intégrale dune fonction continue sur un intervalle quelconque

Propriété de l'intégration d'une fonction intégrable sur un intervalle. Exemple de code python utilisant les module numpy ou le module sympy pour ...



INS1 Introduction à Numpy et Scipy

import scipy.integrate. # Intégration de fonctions ou d'équadiffs. 4 import scipy.optimize. # Zéros et ajustements de fonction.



Utilisation de python pour le calcul numérique

— La librairie SciPy qui s'appuie sur NumPy implémente de nombreuses fonctions de calcul numé- rique (résolution d'équations



Analyse numérique en Python Intégration et dérivation

La fonction permettant de calculer l'intégrale d'une fonction sur un intervalle s'appelle quad et se trouve dans scipy.integrate. Son utilisation est très 



PDF Numerical Integration in Python - halvorsen.blog

These functions typically also use more advanced numerical integration methods than the simple and basic Trapezoid rule. • SciPy has many functions for 



2/28/2021 Lab4 152Overview - Texas A&M University

So our introductory lines will be the following: In [1]: from numpy import * import sympy as sp Let's start by trying to symbolically integrate f(x) Every symbolic command must be prefaced by "sp": In [3]: x=sp symbols('x') f=sp exp(-x**2) sp integrate(f(x02)) Out[3]: sqrt(pi)*erf(2)/2



How to Compute Numerical integration in Numpy (Python)?

•NumPy arrays facilitate advanced mathematical and other types of operations on large numbers of data Typi-cally such operations are executed more ef?ciently and with less code than is possible using Python’s built-in sequences •A growing plethora of scienti?c and mathematical Python-based packages are using NumPy arrays; though



NumPy Reference

NumPy provides an N-dimensional array type the ndarray which describes a collection of “items” of the same type The items can be indexed using for example N integers All ndarrays are homogenous: every item takes up the same size block of memory and all blocks are interpreted in



Numerical Computing in Python - Department of Computer Science

import numpy as np a = np array([[123][456]]dtype=np float32) print a ndim a shape a dtype 1 Arrays can have any number of dimensions including zero (a scalar) 2 Arrays are typed: np uint8 np int64 np float32 np float64 3 Arrays are dense Each element of the array exists and has the same type 12



NumPy Notes - GitHub Pages

NumPy (Numerical Python) is the fundamental package used for scientific computing in Python Numpy offers a number of key features for scientific computing in particularmulti-dimensional ar- rays (or ndarrays in NumPy speak) such as vectors or matrices as well as the attendant operations



An introduction to Numpy and Scipy - UCSB College of Engineering

Sep 20 2022 · NumPy and SciPy are open-source add-on modules to Python that provide common mathematical and numerical routines in pre-compiled fast functions These are highly mature packages that provide numerical functionality that meets or perhaps exceeds that associated with commercial software like MatLab



Numerical Python - Cornell University

This chapter introduces the Numeric Python extension and outlines the rest of the document The Numeric Python extensions (NumPy henceforth) is a set of extensions to the Python programming lan- guage which allows Python programmers to efficiently manipulate large sets of objects organized in grid-like fashion



Multiple Integrals and Probability : A Numerical Exploration

Modify the Python code to perform the three dimensional integral Try and determine how the accuracy of either the two or three dimensionalmethod varies as the number of subintervals is changed 2 Monte Carlo Integration If we have many dimensions it may be expensive to calculate sum over all points (seeSection B)



IntroductIon Chapter to numPy

NumPy arrays are used to store lists of numerical data vectors and matrices The NumPy library has a large set of routines (built-in functions) for creating manipulating and transforming NumPy arrays Python language also has an array data structure but it is not as versatile efficient and useful as the NumPy array The NumPy Contiguous



Introduction to Python: NumPy Pandas and Plotting

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Math 246 Unit 6: De?nite Integrals with the Trapezoid

However in Python ?les and modules it is not possible to use magic commands like pylab and it is best to import items needed explicitly with one of the following patterns illustrated here by plotting the graph of A) import numpy import matplotlib pyplot x = numpy linspace(-numpy pi numpy pi) y = numpy sin(x) matplotlib pyplot plot(x y)



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# in Fortran or C They will thus execute much faster than pure Python code # As a rule of thumb we expect compiled code to be two orders of magnitude # faster than pure Python code # Scipy is built on numpy # All functionality from numpy seems to be available in scipy as well import numpy as np x = np arange(0 10 1 ) y = np sin(x) print(y)

How to calculate numerical integration in NumPy (Python)?

  • How to Compute Numerical integration in Numpy (Python)? The definite integral over a range (a, b) can be considered as the signed area of X-Y plane along the X-axis. The formula to compute the definite integral is: where F () is the antiderivative of f ().

How to find the integral in numpyas?

  • import numpyas np a = 0 b = 1 N = 10 dx = (b -a)/N x = np.linspace(a,b,N+1) y = x**2; A = np.trapz(y,x,dx) print(A) A = 0.33499999999999996 This is a good approximation when we now the exact answer is ,=1/3 We will find the Integral using Python: Given:

What is the indefinite integral in Python?

  • Contents Integrals The Indefinite Integral The indefinite integral of f(x) is a FUNCTION !(#) The Definite Integral The definite integral of f(x) is a NUMBER and represents the area under the curve f(x) from #=&to #=’. Since the topic is Numerical Integration in Python, we will focus on the Definite Integral Where !"($) !& ="($) &is a constant

How to do integrals in SciPy?

  • Scipy has a quick easy way to do integrals. And just so you understand, the probability of finding a single point in that area cannot be one because the idea is that the total area under the curve is one (unless MAYBE it's a delta function). So you should get 0 ? probability of value < 1 for any particular value of interest.
Numerical Integration in PythonHans-Petter Halvorsenhttps://www.halvorsen.blog

https://www.halvorsen.blog/documents/programming/python/Free Textbook with lots of Practical Examples

Additional Python Resourceshttps://www.halvorsen.blog/documents/programming/python/

•Integrals•Numerical Integration•Python ExamplesIt is assumed that already know the basics about integrals from mathematics courses and that you want to use Python to find numerical solutions Contents

IntegralsThe Indefinite IntegralThe indefinite integral of f(x) is a FUNCTION ()⟹$=+The Definite IntegralThe definite integral of f(x) is a NUMBER and represents the area under the curve f(x) from =to =.⟹$!")Since the topic is Numerical Integration in Python, we will focus on the Definite IntegralWhere !"($)!&=()is a constant∫is called the Integral symbol

Integration∫!"=Area under the curve (Yellow color)

ExampleGiven the function:()=We know that the exact solution is:()=*3The integral from 0 to 1 is:(+=13≈0.3333We will take it step by step to see how we can solve this using Python

Example()=(+=13≈0.3333import matplotlib.pyplotas pltimport numpyas npxstart= 0xstop= 1.1increment = 0.1x = np.arange(xstart,xstop,increment)y = x**2plt.plot(x, y)plt.xlabel('x')plt.ylabel('y')plt.axis([0, 1, 0, 1])plt.fill_between(x,y)plt.show()=13≈0.33()='=23

Numerical Integration Approach()'...*+)*,)'*+)*ΔΔΔΔ,)Δ,)-(Δ)+=(Δ+12+-(ΔThis gives:)=(Δ+12)Δ-12(Δ=12(Δ+12)ΔFrom Figure 2:+=((++)Δ2Finally:)Figure 1Figure 2=)+ '... + *Total Area:

Numerical Integration()'...*+)*,)'*+)*ΔΔΔΔ,)Δ,)-(Δ)This gives the total Area under the curve:)=((+))Δ2=8-.)*+)(-/)--)(-/)+-)/2=Δ20#$%&'%#(%+#Typically Δis constant, which gives:=)+ '... + *

Numerical Integration•Given y = f(x) the approximation of the Area (A) under the curve can be found dividing the area up into rectangles and then summing the contribution from all the rectangles•This is known as the Trapezoidrule.!!"=Δ2&!"#$%#!&#+!We will implement and use this rule in Python, both from scratch and using the SciPy library

ExamplesHans-Petter Halvorsenhttps://www.halvorsen.blog

Python Codeimport numpyas npimport matplotlib.pyplotas plta = 0; b = 1N = 10x = np.linspace(a,b,N+1)y = x**2;y_right= y[1:]y_left= y[:-1]# Trapezoid Ruledx = (b -a)/NA = (dx/2) * np.sum(y_right+ y_left)print("A =", A)plt.plot(x,y)plt.xlim([0,1]); plt.ylim([0,1]);Note! You can use semicolon (;) in order to have multiple command at the same line()='A = 0.3350000000000001Which is a good approximation when we now the exact answer is A = 1/3Results from the Python code:

•In the previous example we implemented our own integration from scratch using the Trapezoidrule. That's always a good approach because then we get to know the mathematics behind. •But typically you want to use a predefined function that do the job for you.•These functions typically also use more advanced numerical integration methods than the simple and basic Trapezoid rule.•SciPy has many functions for Numerical Integration•We will use functions in the SciPy Module scipy.integrate•https://docs.scipy.org/doc/scipy/reference/integrate.htmlSciPy

•A = trapz(y,x,∆)-Array of x values-Array of y values∆-The spacing between sample point•https://docs.scipy.org/doc/scipy/reference/generated/scipy.integrate.trapz.html#scipy.integrate.trapztrapz()FunctionWe start with using the built-in Trapezoid rule function trapz():

Python Code -trapz()import numpyas npa = 0b = 1N = 10dx = (b -a)/Nx = np.linspace(a,b,N+1)y = x**2;A = np.trapz(y,x,dx)print(A))='A = 0.33499999999999996This is a good approximation when we now the exact answer is =1/3(+=?We will find the Integral using Python:Given:

•A,err= quad(f, a, b)-Function that shall be integrated-Lower Limit of Integration-Upper Limit of Integration•https://docs.scipy.org/doc/scipy/reference/generated/scipy.integrate.quad.html#scipy.integrate.quadquad()Function

Python Code -quad()from scipyimport integratea = 0; b = 1def y(x):return x**2A, e = integrate.quad(y, a, b)print("A =", A))='A = 0.33333333333333337This is a very good approximation when we now the exact answer is A = 1/3(+=?We will find the Integral using Python:Given:

SciPy -Functions OverviewThere are lots of other functions you can use. I leave to you to try some of these: https://docs.scipy.org/doc/scipy/reference/integrate.html

Practical ExampleHans-Petter Halvorsenhttps://www.halvorsen.blog

Engine ExampleGiven a piston cylinder device (e.g., it could be a car or a motorcycle): We want to find the work produced () in this piston cylinder deviceThe amount of work (W) done is equal to the product of the force () exerted on the piston times the distance () the piston is moved: =×The pressure () the gas exerts on the piston is equal to the force()with which it pushes up on the piston divided by the surface area () of the piston: ="0This gives: =×=(×)×The work produced will then be: =∆

Engine ExampleGiven a piston cylinder device (e.g., it could be a car or a motorcycle): We want to find the work produced () in this piston cylinder deviceThe work produced will then be: =∆The work produced based on the change in volume from )to 'is then:=!"

Engine ExampleGiven a piston cylinder device (e.g., it could be a car or a motorcycle): We want to find the work produced () in this piston cylinder device=+!!!"We can use the ideal gas law: =,i.e., =*123We also assume that the piston contains 1 kmolof gas at 300Kand that the temperature is constant during the process. !=1",#=5"= Pressure= Volume, m3 = Number of moles, kmol= Universal gas constant, 8.314 kJ/kmolK= Temperature, KThis gives:=+!!!"

Python Codefrom scipyimport integrateV1 = 1 V2 = 5 n = 1R = 8.314T = 300def work_eq(V, n, R, T):W = (n*R*T)/V return WW, e = integrate.quad(work_eq, V1, V2, args=(n, R, T,))print("W =", W)W = 4014.2600411931353=3!3"Parameters used:=1=300=8.314/)=14'=54The resulting work becomes:=4014.3

Integration on PolynomialsHans-Petter Halvorsenhttps://www.halvorsen.blog

PolynomialsA polynomial is expressed as:=%&+&'%+⋯+&+&(%where %,,3,...are the coefficients of the polynomial.In Python we can use the polyint()function to perform integration on polynomials. This function works the same way as the polyder()function which performs differentiation on polynomials.

Basic Integration Rule=!Examples:=24⟹=245(=1+1&(%=⟹=12'='⟹=134etc.=3'⟹=3134=4

Basic Integration Rule=!etc.)Q=1+1RS+)Q=⟹∫+=++=+2-+1=2-+=*Examples:=⟹∫(+=+**(+=+*1-+*0*=+*

ExampleGiven the following polynomial:="+2#-+3The exact solution is:=+$%"+2#-+3)==&4+2"3-#2+3$%=14&-&+23"-"-12#-#+3-)=-1and =1gives:=141-1+231+1-121-1+31+1=223≈7.33

ExampleGiven the following polynomial:="+2#-+3Note!!! In order to use it in Python, we reformulate:=3-+2#+"The Indefinite Integral is:∫=3-'##+ #""+ '&&The Definite Integral is:+('')=F3-12#+23"+14&(''=223≈7.33

Pythonimport numpy.polynomial.polynomialas polyp = [3, -1, 2, 1]# Find Indefinite integralI = poly.polyint(p)print("I =", I)# Find Definite integrala = -1b = 1A = poly.polyval(b, I) -poly.polyval(a, I)print("A =", A)The Python solution:I = [ 0. 3. -0.5 0.66666667 0.25 ]A = 7.333333333333333The Indefinite Integral is:∫=3-#$$+ $%%+ #&&The Definite Integral is:''##()=*3-12$+23%+14&'##=223≈7.33=3-+2+*

Additional Python Resourceshttps://www.halvorsen.blog/documents/programming/python/

Hans-Petter HalvorsenUniversity of South-Eastern Norwaywww.usn.noE-mail: hans.p.halvorsen@usn.noWeb: https://www.halvorsen.blog

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