{"record":{"id":"56dc30577a71c6f6","repo":"huggingface/pytorch-image-models","slug":"invalid-beta-parameter-at-index-0-56dc30","errorCode":null,"errorMessage":"Invalid beta parameter at index 0: {}","messagePattern":"Invalid beta parameter at index 0: (.+?)","errorType":"validation","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"timm/optim/mars.py","lineNumber":117,"sourceCode":"            self,\n            params: ParamsT,\n            lr: float = 3e-3,\n            betas: Tuple[float, float] = (0.9, 0.99),\n            eps: float = 1e-8,\n            weight_decay: float = 0.,\n            gamma: float = 0.025,\n            mars_type: str = \"adamw\",\n            optimize_1d: bool = False,\n            lr_1d_factor: float = 1.0,\n            betas_1d: Optional[Tuple[float, float]] = None,\n            caution: bool = False\n    ):\n        if not 0.0 <= lr:\n            raise ValueError(\"Invalid learning rate: {}\".format(lr))\n        if not 0.0 <= eps:\n            raise ValueError(\"Invalid epsilon value: {}\".format(eps))\n        if not 0.0 <= betas[0] < 1.0:\n            raise ValueError(\"Invalid beta parameter at index 0: {}\".format(betas[0]))\n        if not 0.0 <= betas[1] < 1.0:\n            raise ValueError(\"Invalid beta parameter at index 1: {}\".format(betas[1]))\n        assert mars_type in [\"adamw\", \"lion\"], \"MARS type not supported\"\n\n        defaults = dict(\n            lr=lr,\n            betas=betas,\n            eps=eps,\n            weight_decay=weight_decay,\n            mars_type=mars_type,\n            gamma=gamma,\n            optimize_1d=optimize_1d,\n            lr_1d_factor=lr_1d_factor,\n            betas_1d=betas_1d or betas,\n            caution=caution,\n        )\n        super(Mars, self).__init__(params, defaults)\n","sourceCodeStart":99,"sourceCodeEnd":135,"githubUrl":"https://github.com/huggingface/pytorch-image-models/blob/9a5261e31b3b5128526eb2658333b4c0a54464ae/timm/optim/mars.py#L99-L135","documentation":"Mars requires beta1 (betas[0]) to satisfy 0 <= beta1 < 1, the standard constraint for exponential-moving-average decay coefficients. Values outside this range produce non-convergent momentum estimates.","triggerScenarios":"Calling Mars(params, betas=(1.0, 0.999)) or betas=(-0.1, 0.999); beta1=1 is explicitly rejected.","commonSituations":"Copying betas from a config where beta1 was set to 1 for 'full momentum'; ordering mixups passing (beta2, beta1).","solutions":["Use betas with beta1 in [0,1), e.g. (0.9, 0.999)","Verify you passed (beta1, beta2) in the right order","Check Mars-specific betas_1d if you also configure the 1D param group"],"exampleFix":"# before\nopt = Mars(model.parameters(), betas=(1.0, 0.999))\n# after\nopt = Mars(model.parameters(), betas=(0.9, 0.999))","handlingStrategy":"validation","validationCode":"b1, b2 = cfg.betas\nassert 0 <= b1 < 1 and 0 <= b2 < 1, 'betas must be in [0,1)'","typeGuard":"def are_valid_betas(betas: tuple) -> bool:\n    return (len(betas) == 2 and all(isinstance(b, (int, float)) and 0 <= b < 1 for b in betas))","tryCatchPattern":null,"preventionTips":["Validate betas tuple order and bounds in config schema","Remember both betas and betas_1d are validated"],"tags":["optimizer","mars","betas","hyperparameter-validation"],"backgroundTag":"hyperparameter-out-of-range","analyzedSha":"9a5261e31b3b5128526eb2658333b4c0a54464ae","analyzedAt":"2026-08-27T02:34:25.417Z","schemaVersion":2},"datasetVersion":"2026-08-27T03:17:27.898Z"}