Accuracy of Free42 and DM42
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12-20-2017, 08:16 PM
(This post was last modified: 12-20-2017 08:18 PM by Dieter.)
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Accuracy of Free42 and DM42
Swiss Micros' DM42 now is available, and its firmware is based on Free42 Decimal. This reminds me of a remark (was it by Thomas Okken himself?), saying that Free42 works with 34 BCD arithmetics, but the implemented algorithms may not always be good for 34 digit accuracy.
So I started my good old 2014 version of Free42 Decimal, and indeed I got some results that were surprisignly inaccurate. For instance sin(45°) and cos(45°). These should equal √½. Direct evaluation of the latter yields the correct value: 0,7071067811865475244008443621048490 This agrees with Wolfram Alpha and the WP34s. But sin(45°) and cos(45°) both return 0,7071067811865475727373109293694142 This means only 16 correct digits and 18 digits of "numeric noise". In my Free42 version, that is. So let me ask two questions: - Does the above result only say that I'm using an outdated version of Free42 and current versions are more accurate, possibly with true 34-digit accuracy? - How does the new DM42 behave in this regard? Dieter |
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