exp Generator

The exp generator uses a Taylor series approximation to calculate the fixed point value of the natural exponential function e^x. The Maclaurin series for the function can be written as:

e^x = 1 + x + x^2/2! + x^3/3! + ... + x^n/n!

where n is the nth degree or order of the polynomial.

For signed values, we can take the reciprocal value:

e^(-x) = 1/e^x

The gen_exp.py file can generate an entire Calyx program for testing purposes. The main component contains memories x (for the input) and ret for the result of e^x. In order to generate an example program with degree 4, bit width 32, integer bit width 16, and x interpreted as a signed value:

./calyx-py/calyx/gen_exp.py -d 4 -w 32 -i 16 -s true

Similarly, it provides a function to produce only the necessary components to be dropped into other Calyx programs.

Installation

Install the calyx-py library.

Command Line Options

The command line options configure the degree (or order) of the taylor series, bit width, integer bit width, and sign.

  • --degree: The degree of the Taylor polynomial.
  • --width: The bit width of the value x.
  • --int_width: The integer bit width of the value x. The fractional bit width is then inferred as width - int_width.
  • --is_signed: The signed interpretation of the value x. If x is a signed value, this should be true and otherwise, false.