If you do all the calculations in regular LV functions rather than in the formula node, you can use Extended Precision data types. That changes the 17th digit right of the decimal point.
When I look at the data at intermediate steps (the individual terms summed to get e_ITS90) I see that the spreadsheet matches to 7 to 13 significnat digits, depending on the exponent. Note that for the third term (with exponent = 0), the spreadsheet calculation does not return the g2 coefficient: g2 = 19.542636 and g2*x^0 = 19.54263612. I set up a column in the spread sheet with the values equal to the g[i] coefficients but displayed with as many digits as the spreadsheet allows. g1, g2, and g3 differ from what is entered in column C in the first several digits to the right of the last digit entered. When I do the same thing in LV, the differences tend to be in the 15th or 16th digit.
All of these things are the result of the way numeric data is represented in the computer, as Jeff pointed out earlier. It appears that you can get somewhat more precison in LV than in the spreadsheet. I did not do any accuracy checking.
Lynn
