AfDalDecimal * afdal_decimal_make_negative AfDalDecimal decimal  ) 

Allows to transform a positive value into a negative value.

This function allows to get a negative representation from a positive representation. It doesn't do an arithmetic operation to obtain the result.

This function tries first to figure out if the given decimal value is a positive one.

Once done, the function normalizes the number and prepend the negative sign to the current normalized representation.

If the number is already negative, the function just returns without error.

decimal the AfDalDecimal value to transform into a negative.
the function returns the new posite AfDalDecimal value. In the case the given value is already negative the function retuns NULL.