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Common Errors

When to use this page

Use this page when you encounter an error from mechestim and need to understand what went wrong.

BudgetExhaustedError

Symptom:

mechestim.errors.BudgetExhaustedError: einsum would cost 16,777,216 FLOPs but only 1,000,000 remain

Why: The operation you called would exceed the remaining FLOP budget. The operation did not execute.

Fix: Increase flop_budget in your BudgetContext, or reduce the cost of your computation. Use budget.summary() to see which operations are consuming the most FLOPs.

NoBudgetContextError

Symptom:

mechestim.errors.NoBudgetContextError: No active BudgetContext. Wrap your code in `with mechestim.BudgetContext(...):`

Why: A counted operation (like me.einsum, me.exp, etc.) was called with no active budget session.

In the core library: This error is unlikely in normal use. mechestim automatically activates a global default budget, so operations run freely without any explicit setup. If you do see this error in the core library, it may indicate the global default was somehow torn down — restarting your session should resolve it.

In the client-server model: The server requires an open session. If your code runs on the server without a BudgetContext, this error will fire. Fix it by wrapping your computation:

with me.BudgetContext(flop_budget=10_000_000) as budget:
    # your code here

AttributeError: module 'mechestim' has no attribute '...'

Symptom:

AttributeError: module 'mechestim' has no attribute 'save'. mechestim does not support this operation.

Why: The NumPy function you're trying to use is blocked by mechestim (I/O, config, and system-level functions are not part of the competition API).

Fix: Check Operation Categories for supported operations, or see the Operation Audit for the complete list.

RuntimeError: Cannot nest BudgetContexts

Symptom:

RuntimeError: Cannot nest BudgetContexts

Why: You opened a BudgetContext inside another explicit BudgetContext. This error can only arise when two explicit contexts overlap.

Note: If the global default budget is active (the normal case in the core library), opening an explicit BudgetContext is fine — it temporarily replaces the global default for the duration of the with block, then restores it on exit. This is not nesting and does not raise an error.

Fix: If you see this error, you have two explicit BudgetContext managers open at the same time. Restructure your code so only one explicit context is active at a time, or rely on the global default for the outer scope.

SymmetryError

Symptom:

mechestim.errors.SymmetryError: Tensor not symmetric along axes (0, 1): max deviation = 0.5

Why: You called me.as_symmetric() to declare that a tensor is symmetric along certain axes, but the actual data does not satisfy the symmetry within tolerance.

Fix: Verify that the tensor truly has the claimed symmetry (e.g., A[i,j] == A[j,i]). If it's approximately symmetric, you may need to symmetrise it first: A = (A + A.T) / 2.