# Questions tagged [scipy]

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

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### Large residual when integrating 2nd order ode close to singularity with SciPy ode / ODEPACK

I am trying to integrate a 2nd order ODE with a singularity at close to the initial condition. Why do I get large residuals when I plug-in the result of my integration back into the ODE? The equation ...
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### 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 ...
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### 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 ...
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### 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: ...
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### 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. ...
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### ILUTP in sparse.linalg.spilu?

In Matlab, an ILU with threshold and pivoting (ILUTP) can be passed by default as: setup.type = 'ilutp'; [L, U] = ilu(A, setup); Looking for an equivalent in ...
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### 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 ...
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60 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 ...
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### 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\...
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### Applying the result of Cuthill-McKee in SciPy (followup)

This is a followup to Applying the result of Cuthill-McKee in SciPy , where I'm not sure the answer given is correct. It's also 4 years old, so I'm trying a new question. The question is still ...
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105 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,...
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123 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 ...
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### Comparing custom linear regression solver to SciPy equivalent in Python

From a given data set, I set out to complete a task which is below Fit the data of the previous exercise to fit Eq. (8.18) using the SciPy function ...
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### Scipy.integrate.odeint is returning curves with almost the same frequency for different damping ratios, shouldn't they be different?

I am trying to solve the ODE for a harmonic oscillator using Scipy's odeint solver for different dampening factors. I'm using the following code, based off of this example: ...
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38 views

### How to handle system of chemical reactions for a batch reactor SciPy solver

I have a system of chemical reactions where the rate equations represent a batch reactor model. The model is a system of ODEs which is solved with the SciPy ...
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### Time sampling changes solution

I'm currently trying to solve a problem using numerical methods. The set-up is rather long, so I apologize in advance... TL;DR: My solutions change depending on how big my steps are and I don't know ...
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909 views

### Tridiagonal Solver in Python

I have a code I'm working on that involves solving a 1D Schrodinger equation using a Crank-Nicolson time step. The code is written in NumPy/SciPy, and I was doing a bit of profiling and discovered ...
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### scipy.optimize.minimize(method=“SLSQP”) does not give the minimal value along its own search path

I would like to enquire about a situation I encountered while using the scipy function scipy.optimize.minimize(method="SLSQP"). It seems to loose track of the global minimum in the path of ...
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### Scipy: Sampling a custom distribution

Using Scipy, I would like to draw a random sample according to a certain probability density. The probability density function I consider is defined on the real line and depends on k parameters that I ...