ICSILog

ICSILog is a C-language implementation of a fast single-precision approximation of the natural logarithm with adjustable accuracy. The core idea is to use a quantized version of the mantissa of the input floating point number as a pointer into a lookup table. The amount of quantization of the mantissa determines the table size and therefore the accuracy. Current processors are able to store relatively large lookup tables in cache memory. Therefore an acceptable accuracy can be reached without too many main memory accesses.