Fcn.md

@@ -8,6 +8,8 @@ The module supports a number of different types of mathematical functions:
 - Floating-point absolute values ( `fabs()` )
 - Logarithm  base 10 (  `log10` )
 - Square root ( `sqrt()` )
+- ***Single argument*** LIGO math functions defined in the `inlineMath_x86_asm.h` header
+    - For the functions named above you must use the non-LIGO name, ex `sin()` instead of `lsin()` as the RCG does the conversion
 - Combinations of the above functions and constants
 
 ## Operation