A matrix embedding refers to stacking multiple embeddings into a matrix form. This is common when dealing with sequences like:

• Sentences (word embeddings stacked into a 2D matrix)
• Paragraphs (sentence embeddings stacked)
• Users/items in recommender systems

Shape example:

If you have a sentence of 10 words and each word embedding is 300-dimensional, the sentence embedding matrix is:

shape = (10, 300)