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#1
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Excel makes an error
I am currious to find an explanation for this. In excel I created a
simple formula to calculate 12 to the 19th power written in full numerical form. At 12 to the 17th excel makes an error (note the zero's). Try it yourself. Anyone know why this happens? 12 144.00 1728.00 20736.00 248832.00 2985984.00 35831808.00 429981696.00 5159780352.00 61917364224.00 743008370688.00 8916100448256.00 106993205379072.00 1283918464548860.00 <-- here is where the error starts, the number should end with 864.00 15407021574586400.00 184884258895036000.00 2218611106740440000.00 26623333280885200000.00 319479999370623000000.00 Try this with any really large number. The calculations drop off at the 17th digit. I've tried this on different computers all with the same result. |
#2
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Excel makes an error
XL can only return 15 digits of accuracy.
-- HTH, RD --------------------------------------------------------------------------- Please keep all correspondence within the NewsGroup, so all may benefit ! --------------------------------------------------------------------------- wrote in message ups.com... I am currious to find an explanation for this. In excel I created a simple formula to calculate 12 to the 19th power written in full numerical form. At 12 to the 17th excel makes an error (note the zero's). Try it yourself. Anyone know why this happens? 12 144.00 1728.00 20736.00 248832.00 2985984.00 35831808.00 429981696.00 5159780352.00 61917364224.00 743008370688.00 8916100448256.00 106993205379072.00 1283918464548860.00 <-- here is where the error starts, the number should end with 864.00 15407021574586400.00 184884258895036000.00 2218611106740440000.00 26623333280885200000.00 319479999370623000000.00 Try this with any really large number. The calculations drop off at the 17th digit. I've tried this on different computers all with the same result. |
#3
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Excel makes an error
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#4
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Excel makes an error
Excel functions here exactly as it is supposed to.
Almost all computer software (including Excel) does binary math, and in particular follows the IEEE standard for double precision representation of floating point numbers. All 15 digit whole numbers can be exactly represented in double precision. Only some 16 digit whole numbers can be exactly represented in double precision; hence the MS decision to display only 15 digits, where many IEEE DP packages will display up to 17 digits. You can use the D2D function at http://groups.google.com/group/micro...06871cf92f8465 to display more digits. For your particular calculation, 12^i = 2^(2*i) * 3^i which means that Excel's calculation should be exact for all i where 3^i can be exactly represented. Specifically, that would be for i<=33. D2D(12^33) = 4.10186270246002225336426103593500672E35 which is exactly correct, whereas D2D(12^34) = 4.922235242952026408889208063769182208E36 is necessarily only an approximation of 4.922235242952026408889208063769182208064E36 Jerry " wrote: I am currious to find an explanation for this. In excel I created a simple formula to calculate 12 to the 19th power written in full numerical form. At 12 to the 17th excel makes an error (note the zero's). Try it yourself. Anyone know why this happens? 12 144.00 1728.00 20736.00 248832.00 2985984.00 35831808.00 429981696.00 5159780352.00 61917364224.00 743008370688.00 8916100448256.00 106993205379072.00 1283918464548860.00 <-- here is where the error starts, the number should end with 864.00 15407021574586400.00 184884258895036000.00 2218611106740440000.00 26623333280885200000.00 319479999370623000000.00 Try this with any really large number. The calculations drop off at the 17th digit. I've tried this on different computers all with the same result. |
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