Complex sentence: Atlas Autocode included a complex data type which would support complex numbers (which use the square root of -1), partly because of pressure from the electrical engineering department, as complex numbers are used to represent the behavior of alternating current.
Split into simpler sentences: Atlas Autocode included a complex data type which would support complex numbers (which use the square root of -1). This was partly because of pressure from the electrical engineering department, as complex numbers are used to represent the behavior of alternating current.