The Atari BASIC (c) 1978, 1979, 1983 that came with the Atari 600 XL homecomputer had the
RAD statements that not only decided upon the unit on input to
COS, but also the unit on output from
Internally to BASIC, the use of Polynomial Evaluation meant degrees could stay degrees, and radians could stay radians. eg. For
COS, they first divide the input by 90 (
DEG) or pi/2 (
RAD). Then they use the quotient mod 4 to establish the quadrant which will enable them to adjust the sine that they calculate using Polynomial Evaluation. All of this uses assembly everywhere which undoubtedly is fastest.
DEG statement not been available, the user that would have preferred working from degrees, would have had to use costly multiplications by pi/180 or 180/pi to convert into or out-of radians. This would have been important in the space-cramped 6502 environment.
In my school we did learn about radians, but we exclusively used degrees. I was very happy that once I had bought the Atari 600 XL, I could just issue a one-time
DEG statement and keep working in the comfort of degrees instead of having to use radians.
My next Atari computer was the 1040ST with the 68000 CPU inside. It came with the Atari ST BASIC (c) 1987. The
RAD statements had gone. Just like any other programming language that I've seen from then on it exclusively worked with radians for its