The various algorithms need different amounts of memory for working space. Let p be the number of parameters estimated and n be the number of observations used in the model estimation.
For the simplex algorithm, the minimum working space (in bytes) needed is
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for the interior point algorithm,
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and for the smoothing algorithm,
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For the last two algorithms, if you want to use preprocessing, an extra amount
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is needed.
If sufficient space is available, the input data set is kept in memory; otherwise, the input data set is reread as necessary, and the execution time of the procedure increases substantially.