The article focuses on texts for algorithms found in the earliest extant mathematical sources in Chinese. It brings to light that texts regularly make use of analogy. On the one hand, the author shows that the texts use several techniques to prescribe by analogy. On the other hand, she highlights that in addition to a prescriptive dimension, these algorithm texts regularly possess an assertive dimension, stating analogies by the way in which they are formulated. She analyses how analogies are thereby stated, proving that commentators on these texts interpreted this dimension of the text and read in it the assertion of an analogy at the level of the reasons underlying the correctness of the algorithm.