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Accuracy and Word Width

The accuracy of the result can be influenced in a considerable way by the word width. For instance when the word width is 32 bits and the integration step h=1s, only the accuracy of computation of the equation (20) shown in Tab.6 can be reached.


Reduced value y(1) ORD Absolute error
2. 1 -7.183E-0001
2. 2 -2.183E-0001
2.7 3 -5.162E-0002
2.71 4 -9.948E-0003
2.718 5 -1.615E-0003
2.7182 6 -2.263E-0004
2.7182 7 -2.785E-0005
2.718281 8 -3.053E-0006
2.718281 9 -2.980E-0007
2.7182818 10 -2.421E-0008
2.71828182 11 1.863E-0009
2.71828182 12 1.863E-0009
2.71828182 13 1.863E-0009




Tab.6: 32 bit arithmetic

With a specially constructed 128-bit arithmetic a very high computation accuracy for the equation (20) can be reached even with the integration step h=1s (Tab.7).

Given an integration step h, it is very important


Reduced value y(1) ORD Abs err
2. 1 -7.183E-0001
2. 2 -2.183E-0001
2.7 3 -5.162E-0002
2.71 4 -9.948E-0003
2.718 5 -1.615E-0003
2.7182 6 -2.663E-0004
2.7182 7 -2.786E-0005
2.718281 8 -3.059E-0006
2.7182818 9 -3.029E-0007
2.71828182 10 -2.731E-0008
2.718281828 11 -2.261E-0009
2.7182818284 12 -1.729E-0010
2.71828182845 13 -1.229E-0011
2.71828182845 14 -8.155E-0013
2.71828182845904 15 -5.077E-0014
2.718281828459045 16 -2.976E-0015
2.7182818284590452 17 -1.648E-0016
2.71828182845904523 18 -8.652E-0018
2.7182818284590452353 19 -4.315E-0019
2.7182818284590452353 20 -2.050E-0020
2.7182818284590452353602 21 -9.300E-0022
2.71828182845904523536028 22 -4.036E-0023
2.7182818284590452353602874 23 -1.679E-0024
2.7182818284590452353602874 24 -6.704E-0026
2.718281828459045235360287471 25 -2.575E-0027
2.7182818284590452353602874713 26 -9.523E-0029
2.718281828459045235360287471352 27 -3.397E-0030
2.7182818284590452353602874713526 28 -1.170E-0031
2.718281828459045235360287471352662 29 -3.896E-0033
2.71828182845904523536028747135266249 30 -1.255E-0034
2.718281828459045235360287471352662497 31 -3.910E-0036
2.7182818284590452353602874713526624977 32 -1.102E-0037
2.7182818284590452353602874713526624977 33 4.408E-0039
2.7182818284590452353602874713526624977 34 4.408E-0039
2.7182818284590452353602874713526624977 35 4.408E-0039




Tab.7: 128 bit arithmetic


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Next: Evaluation of the Computation Up: Homogenous Equation - Example Previous: Homogenous Equation - Example