Questions tagged [scipy]

SciPy is a Python-based ecosystem of open-source software for mathematics, science, and engineering.

Filter by
Sorted by
Tagged with
4
votes
0answers
38 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 ...
1
vote
1answer
57 views

solve_ivp doesn't work with toms748

I have the following code ...
2
votes
1answer
85 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 ...
3
votes
1answer
362 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 ...
2
votes
2answers
165 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 $\det(X)=\pm\det(S)$...
4
votes
0answers
40 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 $\lambda_\textrm{i}$, ...
1
vote
0answers
29 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 ...
1
vote
1answer
196 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
1answer
29 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
2answers
44 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 ...
1
vote
1answer
100 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 ...
-1
votes
1answer
174 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
1answer
88 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....
-1
votes
1answer
278 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 ...
-2
votes
2answers
90 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
1answer
69 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)...
2
votes
3answers
183 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
0answers
68 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 ...
3
votes
0answers
66 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 ...
3
votes
1answer
108 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 $L$ ...
0
votes
1answer
236 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 ...
-1
votes
1answer
100 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
0answers
57 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: ...
2
votes
0answers
91 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 ...
0
votes
0answers
65 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 ...
0
votes
2answers
88 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 ...
3
votes
0answers
95 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. ...
-1
votes
1answer
244 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
1answer
94 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
1answer
152 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} (...
-1
votes
1answer
902 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
1answer
190 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
1answer
391 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 ...
14
votes
3answers
5k 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 ...
1
vote
1answer
156 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
1answer
217 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 ...
0
votes
1answer
241 views

SciPy odeint fails in unpredictable ways on deterministic system of ODEs

I've been trying to solve the following (relatively simple) system of Lotka-Volterra ODEs in Python using SciPy's odeint: $$\dot{z_1} = z_1 \left(- \sigma z_1 + \sigma z_2 + \rho z_3 - z_4 - z_5\right)...
1
vote
1answer
291 views

Is there a way to bound the values of a variable when using scipy.integrate.solve_ivp in python?

I want to solve an IVP in python with two variables, x and u, but I need the values of u to be between 0 and 1. Right now it is giving me a solution with negative values for u. Here is the code I have....
1
vote
1answer
688 views

scipy odeint: excess work done on this call and very sensitive to initial value

I am trying out odeint and received the error 'Excess work done on this call (perhaps wrong Dfun type).'. The values returned are also super sensitive to small ...
1
vote
1answer
890 views

Numerical integration problem: IntegrationWarning The integral is probably divergent, or slowly convergent

I am trying to get the numerical integration of a function using scipy's integrate.quad as follows. $$ \begin{equation} G (\alpha) = \frac{4\alpha}{\pi}\int_0^{\...
2
votes
0answers
32 views

Scaling tensor approximation by symmetric tensor decomposition with SciPy's L-BFGS-B

I am trying to approximate a symmetric tensor of which the values are in the range of [1e-7,1e-4], by a symmetric tensor decomposition of lower rank. For this I am using the L-BFGS-B method in SciPy's ...
0
votes
1answer
119 views

Odeint error for nonlineal differential equations

I receive the following error when I run the code. ODEintWarning: Excess work done on this call (perhaps wrong Dfun type). Run with full_output = 1 to get quantitative information. warnings.warn(...
2
votes
2answers
491 views

Python scipy eigh(Arpack) giving wrong eigenvalues for generalized eigenvalue problem

I am trying to solve a generalized eigenvalue problem using Arpack, right now the code is using LAPACK but that's too slow, we only need a few eigenvalues and the matrices are sparse so using Arpack ...
3
votes
1answer
144 views

How to get a more accurate cancelation

I shall try to get to the point, so let me know if there is something left and you need more details. I am solving a couple of equations that are not coupled explicitly, but their corresponding ...
1
vote
1answer
413 views

DOP853 integration method is missing (SciPy)

I was checking some integration methods provided by SciPy, in which the DOP853 should be included according to the webpage (https://docs.scipy.org/doc/scipy/reference/generated/scipy.integrate....
0
votes
0answers
29 views

Set of integrators do not consistently solve an equation in Python

I must solve the following second order differential equation: $\delta \phi^{''}_{\mathbf{k}}+(3-\epsilon)\delta \phi^{'}_{\mathbf{k}}+\left(\frac{k^2}{a^2 H^2}+\frac{V_{,\phi\phi}}{H^2}-6\epsilon +4\...
0
votes
1answer
335 views

How to use cumtrapz correctly?

I have tried to do a trapeze integration with f(x)=x^2, where I know how the antiderivative looks like, so F(x) = (1/3)x^3 Here's my code, just like I tried: ...
2
votes
0answers
73 views

Non-negative Least Squares to perform Inverse Laplace with weights

I'm trying to perform the inverse Laplace transform of a (noisy) dataset $y_i$ using Tikhonov regularization: $$\min \sum_{i=1}^{N} \left(\int_0^\infty e^{-s_i t} f(t) \, dt - y_i \right)^2 - \lambda^...
0
votes
0answers
148 views

scipy's solve_ivp returns erroneous results for a stiff differential equation

I'm using scipy's solve_ivp for solving a stiff differential equation. I'm using method BDF for solving the same. I have already used MATLAB's ode23s and I'm getting correct results in MATLAB. However,...
0
votes
0answers
151 views

A parallelized GMRES solver?

My application calls for solving a dense, 40,000 x 40,000, ill-conditioned linear system. The native SciPy GMRES solver with preconditioning has worked well for my application and solving a single ...

1
2 3 4 5