Python: Semidefinite program with CVXPy 'Error parsing inputs'

In summary, the error 'Error parsing inputs' in CVXPy is occurring due to a compatibility issue between the package and the Google Colab Python 3.7 environment. This issue does not occur when using a local Jupyter Notebook environment with Python 3.9.
  • #1
Master1022
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TL;DR Summary
I am trying to run a semidefinite program in Python using CVXPy. I have gone to the documentation and the example code in there doesn't run in Google Colab for me and yields the error: 'Error parsing inputs'.
Hi,

Question:
Why is the error 'Error parsing inputs' in CVXPy occurring?

Context:
I am trying to solve a semidefinite program in CVXPy (using Google Colab). I went to the documentation (HERE) and I copied the example code into a cell. It doesn't work for some reason and I don't understand why. It is throwing the following message: 'Error parsing inputs'. Why is this happening?

Code:
CVXPy Semidefinite Code Documentation Example:
# Import packages.
import cvxpy as cp
import numpy as np

# Generate a random SDP.
n = 3
p = 3
np.random.seed(1)
C = np.random.randn(n, n)
A = []
b = []
for i in range(p):
    A.append(np.random.randn(n, n))
    b.append(np.random.randn())

# Define and solve the CVXPY problem.
# Create a symmetric matrix variable.
X = cp.Variable((n,n), symmetric=True)
# The operator >> denotes matrix inequality.
constraints = [X >> 0]
constraints += [
    cp.trace(A[i] @ X) == b[i] for i in range(p)
]
prob = cp.Problem(cp.Minimize(cp.trace(C @ X)),
                  constraints)
prob.solve()

# Print result.
print("The optimal value is", prob.value)
print("A solution X is")
print(X.value)
Any help would be greatly appreciated
 
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  • #2
This appears to be a compatibility problem with the cvxpy package and the Google Colab Python 3.7 environment. It works for me in a local Jupyter Notebook environment (Python 3.9).
 
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Likes Master1022 and berkeman
  • #3
pbuk said:
This appears to be a compatibility problem with the cvxpy package and the Google Colab Python 3.7 environment. It works for me in a local Jupyter Notebook environment (Python 3.9).
Thanks for the reply @pbuk ! That's correct - when I used a version on my local machine via a conda environment, then it worked
 

Related to Python: Semidefinite program with CVXPy 'Error parsing inputs'

1. What is a semidefinite program?

A semidefinite program is a mathematical optimization problem that involves finding the minimum of a linear objective function subject to linear constraints and a semidefinite constraint. This type of problem arises in many areas of science and engineering, including control theory, signal processing, and machine learning.

2. What is CVXPy?

CVXPy is a Python-embedded modeling language for convex optimization problems. It allows users to express optimization problems in a natural mathematical syntax and then solve them using a variety of efficient solvers.

3. What does the error "Error parsing inputs" mean?

This error means that there was an issue with the input data or syntax in the semidefinite program. CVXPy is unable to process the inputs and therefore cannot solve the problem. This could be due to a variety of reasons, such as missing or incorrect data, or using incompatible data types.

4. How can I fix the "Error parsing inputs" error?

To fix this error, you will need to carefully review your code and the input data to identify any issues or errors. Make sure that all data types are compatible and that there are no missing or incorrect values. You may also need to consult the CVXPy documentation or seek help from a more experienced user or a forum to troubleshoot the issue.

5. Are there any common mistakes that lead to the "Error parsing inputs" error?

Yes, there are a few common mistakes that can lead to this error. These include using incompatible data types, missing or incorrect data, and errors in the mathematical syntax used to express the problem. It is important to carefully review your code and the input data to identify and fix any potential issues before running the optimization problem.

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