Metrohm 848 Titrino plus - Manual (Page 138)

10.8 Arithmetic algorithms in the 848 Titrino plus
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848 Titrino plus
imal difference may arise between an originally entered decimal number
and the internal computer representation in complete accuracy in the
range of the rear decimal places. This difference results from the fact that
an exact binary equivalent does not exist for every decimal number. If, for
example, you enter the sample size 50.3 mg, this will be depicted in the
calculation report in "double precision" with 5.02999999999999E+01.
Rounding-off process
Measured values and results are rounded to the defined number of deci-
mal places (commercial rounding, in accordance with the US Pharmaco-
peia USP). If the digit at the first dropped decimal place is 1, 2, 3 or 4,
then it will be rounded off; if this digit is 5, 6, 7, 8 or 9, then it will be
rounded up. Negative digits will be rounded in accordance with their
amount, i.e. away from zero.
Examples:
2.33 yields 2.3
2.35 yields 2.4
2.47 yields 2.5
–2.38 yields –2.4
–2.45 yields –2.5
Statistics
The arithmetic mean value and the absolute and relative standard devia-
tions of results are calculated:
You can statistically evaluate a maximum of five results (1 ≤ k ≤ 5) calcula-
ted in a determination. A statistical series can contain a maximum of 20
determinations (1
≤ n ≤ 20).
The following convention applies to the subsequent formulas:
1 ≤ n ≤ 20 and 1 ≤ k ≤ 5.
Mean value:
Absolute standard deviation:
Relative standard deviation (in %):
Explanations
The individual values are incorporated in the statistics with full accuracy.