Abu Mohammed Abdallah ibn Mohammed ibn Hajjaj a-Adrini (died 1204) was a Moroccan mathematician of Berber

Berber people

Berbers are the indigenous peoples of North Africa west of the Nile Valley. They are continuously distributed from the Atlantic to the Siwa oasis, in Egypt, and from the Mediterranean to the Niger River. Historically they spoke the Berber language or varieties of it, which together form a branch...

 origin. His place of birth is unknown, but he received his education in Sevilla, Spain.

His most important work is Talqih al-afkar bi rushum huruf al-ghubar (Fertilization of Thoughts with the Help of Dust Letters (Hindu Numerals)). It is a book of two hundred folios about (among other things) the science of calculation

Calculation

A calculation is a deliberate process for transforming one or more inputs into one or more results, with variable change.The term is used in a variety of senses, from the very definite arithmetical calculation of using an algorithm to the vague heuristics of calculating a strategy in a competition...

 and geometry

Geometry

Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....

. He also wrote three poems (urzaja), one on algebra, one on irrational quadratic numbers

Quadratic irrational

In mathematics, a quadratic irrational is an irrational number that is the solution to some quadratic equation with rational coefficients...

 and one on the method of false position.