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Left To Right Comparison of Algebraic Data

IP.com Disclosure Number: IPCOM000096388D
Original Publication Date: 1963-May-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 3 page(s) / 70K

Publishing Venue

IBM

Related People

Riekert, RH: AUTHOR [+2]

Abstract

The arrangement effects left to right serial by character, greater than, less than, equal to compare of variable field length algebraic quantities. The same circuitry is employed as is for an alphanumeric compare. Normally, algebraic comparison is done by a subtraction. However, use of a straight alphanumeric compare should be faster, since this involves only the comparing of characters and no processing is necessary.

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Left To Right Comparison of Algebraic Data

The arrangement effects left to right serial by character, greater than, less than, equal to compare of variable field length algebraic quantities. The same circuitry is employed as is for an alphanumeric compare. Normally, algebraic comparison is done by a subtraction. However, use of a straight alphanumeric compare should be faster, since this involves only the comparing of characters and no processing is necessary.

Left to right, i. e., high to low order, operation is valuable for a compare, since the highest order characters are handled first and the comparison can be terminated upon detection of the first pair of corresponding unalike characters. This advantage can also be gained when algebraic comparisons are done by high to low order subtraction. However, additional circuitry is required to terminate the subtraction and interpret the result. This circuitry is not necessary if comparisons are done using the alphanumeric compare.

An algebraic alphanumeric compare can most easily be accomplished if the algebraic quantities are in the normalized form of: E+/-+/-NNMMM... Where: E is normalizing constant +/- is sign of number +/- is sign of exponent N is exponent digit M is mantissa digit Example: +. 313159... x 10' = E + + 01314159... +. 1602... x 10/-18/ = E + - 181602...

The collate sequence must be arranged so that + is greater than - and 9> 8> ---> 1> 0. If the comparison is being made to determine whether two algebraic fields are equal or not, or if the fields are not algebraic as indicated by the absence of the E symbol as the first character of the fields, then the usual alphanumeric comparison based on the collate sequence can be made. If the comparison is done on algebraic fields and it is desired to determine which field is greater, the indication of comparison must be reversed if both numbers are negative, i. e., +12. 34> +11. 27 but -12. 34 < -11. 27. Unequal data fields are handed by the above rules directly assuming that ABCD> ABC for the alphanume...