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A sanity test or sanity check is a basic test to quickly evaluate whether a claim or the result of a calculation can possibly be true. It is a simple check to see if the produced material is rational (that the material's creator was thinking rationally, applying sanity). The point of a sanity test is to rule out certain classes of obviously false results, not to catch every possible error. A rule-of-thumb may be checked to perform the test. The advantage of a sanity test, over performing a complete or rigorous test, is speed. In arithmetic, for example, when multiplying by 9, using the divisibility rule for 9 to verify that the sum of digits of the result is divisible by 9 is a sanity test—it will not catch ''every'' multiplication error, however it's a quick and simple method to discover ''many'' possible errors. In computer science, a ''sanity test'' is a very brief run-through of the functionality of a computer program, system, calculation, or other analysis, to assure that part of the system or methodology works roughly as expected. This is often prior to a more exhaustive round of testing. ==Mathematical== A sanity test can refer to various orders of magnitude and other simple rule-of-thumb devices applied to cross-check mathematical calculations. For example: *If one were to attempt to square 738 and calculated 53,874, a quick sanity check could show that this result cannot be true. Consider that 700 < 738, yet 700² = 7²×100² = 490,000 > 53,874. Since squaring positive integers preserves their inequality, the result cannot be true, and so the calculated result is incorrect. The correct answer, 738² = 544,644, is more than 10 times higher than 53,874, and so the result had been off by an order of magnitude. *In multiplication, 918 × 155 is not 142,135 since 918 is divisible by three but 142,135 is not (digits add up to 16, not a multiple of three). Also, the product must end in the same digit as the product of end-digits 8×5=40, but 142,135 does not end in "0" like "40", while the correct answer does: 918×155=142,290. An even quicker check is that the product of even and odd numbers is even, whereas 142,135 is odd. *The power output of a car cannot be 700 kJ, since that is a measure of energy, not power (energy per unit time). This is a basic application of dimensional analysis. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sanity check」の詳細全文を読む スポンサード リンク
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