archimedes.optimize.LMStatus

class archimedes.optimize.LMStatus(*values)

Status codes for Levenberg-Marquardt optimization results.

These codes follow the MINPACK convention and provide detailed information about the termination condition of the optimization algorithm. Understanding these codes is essential for interpreting optimization results and diagnosing potential issues.

FTOL_REACHED

Both actual and predicted relative reductions in the objective function are at most ftol. This indicates convergence based on minimal improvement in the objective function.

Type:

int = 1

XTOL_REACHED

Relative error between two consecutive parameter iterates is at most xtol. This indicates convergence based on minimal change in the parameters.

Type:

int = 2

BOTH_TOL_REACHED

Both ftol and xtol conditions are satisfied simultaneously. This represents the strongest convergence criterion.

Type:

int = 3

GTOL_REACHED

The cosine of the angle between the gradient and any column of the Jacobian is at most gtol in absolute value. For constrained problems, this applies to the projected gradient. This indicates convergence to a critical point.

Type:

int = 4

MAX_FEVAL

Maximum number of function evaluations (max_nfev) has been reached without achieving convergence. This typically indicates that either more iterations are needed, the tolerances are too tight, or the problem is ill-conditioned.

Type:

int = 5

Notes

Success vs. Failure:

Status codes 1-4 indicate successful convergence, while code 5 indicates failure to converge within the iteration limit. Use the success property to check for overall success.

Interpretation Guide:

• FTOL_REACHED: Good for most applications, indicates objective function has stopped improving significantly

• XTOL_REACHED: May indicate convergence to a local minimum or numerical precision limits

• BOTH_TOL_REACHED: Strongest convergence guarantee

• GTOL_REACHED: Gradient-based convergence, good indicator of optimality conditions

• MAX_FEVAL: Check if more iterations are needed or if the problem requires reformulation

__init__(*args, **kwds)

Methods

conjugate	Returns self, the complex conjugate of any int.
bit_length()	Number of bits necessary to represent self in binary.
bit_count()	Number of ones in the binary representation of the absolute value of self.
to_bytes([length, byteorder, signed])	Return an array of bytes representing an integer.
from_bytes(bytes[, byteorder, signed])	Return the integer represented by the given array of bytes.
as_integer_ratio()	Return a pair of integers, whose ratio is equal to the original int.
is_integer()	Returns True.
__init__(*args, **kwds)

Attributes

real	the real part of a complex number
imag	the imaginary part of a complex number
numerator	the numerator of a rational number in lowest terms
denominator	the denominator of a rational number in lowest terms
message	Get descriptive message for this status code.
success	Check if this status indicates successful convergence.
FTOL_REACHED
XTOL_REACHED
BOTH_TOL_REACHED
GTOL_REACHED
MAX_FEVAL