Questions tagged [scipy]
SciPy is a Python-based ecosystem of open-source software for mathematics, science, and engineering.
219
questions
-1
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1
answer
45
views
Fitting gauss-hermite-parametrization to data?
I want to fit this data.
I have the following model functions. Classic gaussian:
def gauss_model(x, mu, sigma):
return np.exp(-0.5*((x-mu)/sigma)**2)
And ...
- 99
1
vote
1
answer
88
views
Huygens Fresnel Diffraction integral using dblquad in python
I am attempting to create a python function to assist in calculating the following numerical integration of the Huygens Fresnel integral in the form of ...
1
vote
0
answers
66
views
scipy.optimize.minimize fails to converge but result is OK
I am trying to optimize a non-linear least squares problem with scipy.optimize.minimize. I have simplified my actual problem down to the case where I am just computing the top 'principal components' ...
- 119
1
vote
1
answer
78
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Parameter estimation simple theory question related to scipy.optimize.curve_fit
It has been a while since I have done some stats, and I have tried to fit a curve using optimize.curve_fit of parameter estimation. I am also interested in the standard deviation of the fitted ...
- 65
1
vote
1
answer
47
views
Easy way to perform solver over pandas dataframe
I'm moving from Excel to Python and I'm trying to solve these equations:
$$\begin{align}
X_1&=\bigg[\big(3.47-\log(X_2)\big)^2+\big(\log(c)+1.22)^2\bigg]^{0.5}\\
X_2&=\frac{a}{101.32}\bigg(\...
- 113
2
votes
1
answer
107
views
2nd order differential equation coupled to integro-differential equation in python
I'm trying to solve the following equations numerically in python
$$\begin{align}
12\pi\int_0^\infty drf(r)\phi(r)r^4&=E\\
f(r)-\frac{1}{2\mu}\bigg(\frac{d^2\phi(r)}{dr^2}+\frac{2}{r}\frac{d\phi(r)...
- 23
0
votes
1
answer
72
views
Optimal value of parameter/s from a set by scipy.optimize.minimize() method
I have this function $y = \exp(-x)$. I have a list of $x$ values and corresponding $y$ values.
...
0
votes
0
answers
50
views
Help Finding Roots
I need to refine a level curve representing an implicit function that is not numerically solvable in sympy. The initial solution set generated by matplotlib's ...
- 143
2
votes
1
answer
91
views
Finding the correct order of eigenvectors of a parameter-dependent Hermitian matrix
so, I have a symmetric, analytic matrix $\mathbf{H}(x)$ ($x$ is real). Because $\mathbf{H}(x)$ is analytic and $x$ is real, it is possible to find analytic functions for the eigenvectors and the ...
- 53
2
votes
1
answer
41
views
SciPy ODR "Ordinary" Least Squares?
Scipy.odr has a setting for "fit types", including one for ordinary least-squares. This matches with the documentation of ODRPACK (see p. 31, Computational method).
However, the package ...
- 21
2
votes
1
answer
92
views
Can't solve second order differential equation with scipy
Most of my knowledge about numerically solving differential equations is long forgotten. Unfortunately I stumbled upon a physics problem where I need to do exactly that.
I'm trying to describe the ...
- 31
0
votes
0
answers
44
views
Global convergence behavior of several Krylov solvers in scipy.opt
In a context of mechanical simulation, where I solve the stationnary action principle directly (i.e. $\nabla S = 0$ for some scalar fonction $S$), I use the wrapper scipy.optimize.newton_krylov to ...
- 233
3
votes
1
answer
116
views
How to solve a BVP with known parameters?
I need to solve a boundary value problem (BVP) of second order, where the equation depends on several know parameters, which are geometric parameters and material constants.
I would like to solve this ...
- 510
1
vote
0
answers
49
views
Trouble inverting complex matrix with numpy and scipy
I have some matrix-valued, complex data $Z(f)$ with $f\in\{f_0,f_1,\dots\}$ and $Z(f_i)$ being a 3x3 matrix. I require the inverse $Z^{-1}(f)$ in my workflow. After encountering some problems with my ...
- 11
4
votes
0
answers
50
views
How to troubleshoot numerical instability using finite difference for steady-state non-linear heat conduction equation
I have a problem which I believe is numerical instability when trying to solve a heat conduction equation using finite difference. The short version is that when the parameter $I=80.3$ I get the blue ...
- 510
1
vote
1
answer
84
views
2
votes
1
answer
158
views
SciPy odeint giving different results with matrix multiplication
I've asked this at stackoverflow but maybe this community will have a better idea of the answer.
I'm currently trying to develop a function that performs matrix multiplication while expanding a ...
- 123
4
votes
1
answer
3k
views
Why is my curve_fit not producing the covariance matrix and the correct values for the unknown variables?
I am trying to fit supernova data into a scipy.curve_fit function. However, when my code runs, the values of the unknown variables given by ...
- 43
2
votes
2
answers
188
views
Calculate determinant of unitary matrices based on SVD implementation
I have a real square matrix $X$ which I need to perform a Singular Value Decomposition on. Now, performing the operation
$$
X = USV^T
$$
as $U$ and $V$ are orthogonal, we know that $\det(X)=\pm\det(S)$...
- 53
4
votes
0
answers
46
views
Pass forward intermediate results during iterative optimization
To investigate a counter-current flow heat exchanger while considering temperature dependent physical properties (such as specific heat $c_\textrm{p,i}$, heat conductivity $\lambda_\textrm{i}$, ...
- 223
1
vote
0
answers
52
views
How do you correctly implement Scipy's FFT procedures to produce a low-pass filter - image processing
I'm following this low-pass filter example in the text "Image Operators: Image Processing in Python 1st Edition" by Jason M. Kinser, but can't seem to duplicate their results.
The text's ...
- 11
1
vote
1
answer
581
views
solve_ivp from scipy does not integrate the whole range of tspan
I'm trying to use solve_ivp from scipy in Python to solve an IVP. I specified the tspan ...
0
votes
1
answer
59
views
Logistic growth curve using scipy is not quite right
I'm trying to fit a simple logistic growth model to dummy data using Python's Scipy package. The code is shown below, along with the output that I get. The correct ...
1
vote
2
answers
81
views
scipy odeint: excess work done on this call depending on initial values even with analytically solvable ODE
I am trying to solve a differential equation in the form:
dx/dt = funct(x)
using scipy odeint.
However, for some initial values, I get a "ODEintWarning: Excess work done on this call", even ...
- 23
1
vote
1
answer
203
views
Efficiency of scipy.sparse.linalg.expm_multiply with sparse vs unsparse vectors
From the package scipy.sparse.linalg in Python, calling expm_multiply(X, v) allows you to compute the vector ...
- 185
-1
votes
1
answer
232
views
Using ODE to plot particle-motion with scipy.integrate.solve_ivp
My Problem:
A positively charged particle (mass = 2 * 10-27 kg) is moving along the x-axis. It is travelling in a homogenous magnetic field such that the field axis in z-direction. The energy of the ...
-1
votes
1
answer
111
views
Solving ODEs, Rotations, Angular Velocity, Euler Angles
I am implementing a simulation that needs to rotate and object based
on known angular velocity (assumed constant for simplicity). I followed the
ideas given below, pg. 32)
https://graphics.stanford....
- 229
-1
votes
1
answer
571
views
Fitting using curve_fit of scipy in python gives totally different answer for 1/t and t
I was trying to fit some data to a single degree exponential decay function but a*exp(-x*t) and a*exp(-x/t) gives completely ...
- 107
-2
votes
2
answers
99
views
numerical solution for differential equation
I have these 3 equations and i want to solve them with numerical methods. so I am using scipy library but I don't know how to solve 3 equations together.
R, g, sigma and density are constants.
\begin{...
1
vote
1
answer
118
views
Eigenvalue problem for ordinary differential equation
I am trying to compute the natural frequency of a cantilevered beam.
The Euler-Bernoulli equation reduces to the following problem :
$$
v''''=\lambda v, \text{with }, v(0)=0, v'(0)=0, v'''(1)=0,v''(1)...
- 33
2
votes
3
answers
236
views
Solving a PDE with 2 variables, with one variable whose derivative with respect to space is only known
I am trying to solve a PDE of the form
$$\frac{\partial u}{\partial t} = D \frac{\partial^2u}{\partial x^2} + k\ \ \ (1)$$
where only $k$'s first derivative with respect to $x$ is known
$$\frac{\...
3
votes
0
answers
72
views
Does shift-invert method has invertibility issue?
Please note that I have nearly zero background on numerical methods.
I understand the shift invert method as described in SciPy Tutorial
The main argument of the above link is as follows. Suppose we ...
- 171
4
votes
0
answers
76
views
Check if LinearOperator is symmetric
I have a scipy.sparse.linalg.LinearOperator object. I'd like to check if its associated matrix is symmetric without actually instantiating the matrix in the most ...
- 203
3
votes
1
answer
139
views
Lanczos algorithm for finding top eigenvalues of a matrix sum
I am trying to find the top k leading eigenvalues of a NumPy matrix (using python dot product notation) L@L + a*X@X.T, where $L$ ...
- 203
0
votes
1
answer
347
views
Error using scipy.integrate.solve_ivp: index error: the index 0 is out of bounds for axis 0 with size 0
I am recently working on the code based on the stick-slip phenomenon in Python. It's the stick-slip oscillator (chapter 3.4) in https://www.sciencedirect.com/science/article/pii/S0888327020301205.
And ...
- 11
-1
votes
1
answer
140
views
illegal use of ODEINT
given the following system:
$$\frac{dP}{dt} = \alpha P(1-\frac{P}{K}) - \beta P I$$
$$\frac{dI}{dt} = \beta P I - \rho I$$
how do I solve the system numerically. as when I attempt to solve this is the ...
3
votes
0
answers
70
views
Difference between wave vector and density matrix in numerical calculation of Schrödinger equation
I solved Schrödinger equation for a following tow-level time-dependent Hamiltonian numerically in two ways:
...
- 31
2
votes
0
answers
129
views
Providing Jacobian as LinearOperator in scipy.optimize.root
I asked this question a few days ago on stackoverflow, but I figure scicomp.stackexchange is probably a better place. Sorry for the double post.
I want to solve a system of nonlinear equations using ...
- 233
0
votes
0
answers
84
views
L2 norm optimization problem
I have an optimization problem where i need to find an image x, that is very close to x' such that:
monitor(x') is valid but monitor(x) is invalid. (output is valid
when the neural network output is ...
- 1
0
votes
2
answers
129
views
bin 2d array such that each bin contains equal number of samples?
I'm trying to bin a 2d array of points such that each bin has an equal number of samples contained in it. This would mean having bins of differing ranges and possibly shapes.
I have seen this ...
- 11
3
votes
0
answers
104
views
Python routine to calculate shape resonances of H2
I am currently doing a project in which my aim is to write a program that can be used to calculate single and multi-channel shape resonances. So I'm looking at bound states and quasi-bound states.
...
- 31
-1
votes
1
answer
392
views
Integrate function with cumulative distibution function inside
I'm trying to integrate a function which is defined as func in my code below, a cumulative distribution function is inside:
...
-1
votes
1
answer
98
views
Solve integral $ \int_{-\infty}^{\infty} e^{-x^2}dx$
i trying to solve this integral
$$\int_{-\infty}^{\infty} e^{-x^2}dx$$
I'm using this
CODE
...
1
vote
1
answer
205
views
nquad Integration in SciPy
I am trying to self-learn SciPy and evaluate the following quadruple integral using scipy.integrate.nquad:
$$\int_{0}^{1} \int_{0}^{1} \int_{0}^{1} \int_{0}^{1-x} (...
- 15
-1
votes
1
answer
2k
views
ODEintWarning: Excess work done on this call (perhaps wrong Dfun type)
I was messing around with some numerical integration functions. I wrote an arbitrary differential equation to test my understanding, the code is as follows:
...
0
votes
1
answer
204
views
How to compare 2D vector fields and minimize the difference?
I want to compare the field of two electrical currents and compare the resulting field to a magnetic dipol field and find magnetic momentum that minimizes the difference of the two fields.
My current ...
1
vote
1
answer
538
views
Trouble with backwards time integration in Python
I am struggling with a rather basic numerical integration task: Using Python's scipy.integrate.solve_ivp module to integrate an ODE sytem backwards in time. As a test, I am using the following ODE ...
- 143
14
votes
3
answers
6k
views
How are scientific computing workflows faring on Apple's M1 hardware
The initial wave of reviews for Apple's M1 hardware are out, and there's lots of generic benchmarks and data on workflows on professional programs for creative users, but I haven't seen anyone talking ...
- 2,353
1
vote
1
answer
225
views
Help with modified bessel functions
I'm trying to parse the following expression (Eq. 35 in The Magnetic Field in the Vicinity of Parallel and Twisted Three-Wire Cable Carrying Balanced Three-Phased Current) in Python and calculate its ...
3
votes
1
answer
298
views
Good languages/packages for interior point optimization with non-linear constraints?
I'm currently using Python's scipy.optimize package to perform parameter estimation for a system of 10 ODEs. I have some observed data, and I'm trying to find the set of parameters which makes the ODE ...
- 143