ABSTRACT
This chapter discusses the design and development of primitive routines for calculating exponential, trigonometric, and logarithmic functions on the Intel math unit. Exponential functions, such as the calculation of 10y-, ey-, and xy- are essential operations in most mathematical and floating-point packages. In addition, many compilers and interpreters include an exponential operation which allows the calculation of powers and roots, although certain common powers and roots, such as squares, cubes, and square roots, are often provided separately. In the original 8087 and 80287 mathematical coprocessors all trigonometric functions were implemented by means of two elementary instructions: FPTAN to calculate the partial tangent, and FPATAN to calculate the partial arc-tangent. Instructions for calculating trigonometric functions and arcfunctions require radian measure. While radians are a standard representation in many technical, engineering, and scientific fields, non-technical applications often express angles in decimal degrees.
