JP3567576B2 - Electronic computer - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic computer that performs an arithmetic operation on an input operation expression and displays the operation result.
[0002]
[Prior art]
In general, in a computer, when a desired calculation expression is input by key and displayed, and execution of a calculation is instructed, a calculation process is executed by a CPU according to the calculation expression stored in a RAM, and the calculation result is displayed on a display unit. Is done.
[0003]
In this case, various numerical data are temporarily written in, for example, a work area in a RAM, or the numerical data written in this work area is read back into the CPU for arithmetic processing as the arithmetic processing by the CPU progresses. It is necessary to process and exchange various numerical data many times until the calculation result is obtained. For example, the maximum number of storable digits of the numerical data in the work area in the RAM or the maximum processing of the numerical data in the CPU is possible. The number of digits is limited in advance by the specifications of the RAM and the CPU.
[0004]
[Problems to be solved by the invention]
For this reason, the number of digits of numerical data to be processed accompanying the calculation increases, and when the number exceeds the maximum storable number of digits in the RAM or the maximum number of scalable digits in the CPU, the lower limit is exceeded for the number exceeding the maximum possible number of digits. Since the calculation is performed with the digit on the side omitted, that is, a so-called underflow occurs, an accurate calculation result may not be obtained as an answer.
[0005]
FIG. 6 is a diagram showing a calculation display operation accompanying the calculation process of "2 ⁴⁷ " in the conventional computer. FIG. 6A is a diagram showing an input display state of a calculation expression, and FIG. It is a figure showing a display state of a calculation result.
[0006]
When the operator operates the data input key to input an arithmetic expression of “2 ⁴⁷ ” and instructs execution of the operation by the “EXE” key, the answer “1407... 5325” is displayed by the arithmetic processing in the CPU. Has an error due to the effect of digit cancellation, and it is not possible to obtain an accurate answer “1407... 5328” of “2 ⁴⁷ ”.
[0007]
Therefore, in the arithmetic processing with a large number of arithmetic digits, there is a problem that an error due to the effect of the digit drop occurs in the lower digit of the numerical data obtained as an answer.
The present invention has been made in view of the above-described problems, and provides an electronic computer that can obtain an accurate answer even when a digit is lost in the lower digit of numerical data to be processed. Aim.
[0008]
[Means for Solving the Problems]
That is, an electronic computer according to the present invention is an electronic computer that performs arithmetic processing on input arithmetic expression data and displays an arithmetic result, and includes an expression input unit that inputs arithmetic expression data for performing an arithmetic operation, Calculating means for executing the operation of the operation expression data input by the input means; storage means for storing a plurality of predetermined operation data and numerical data in association with each other; Determining means for determining whether or not the expression data matches any of the plurality of operation data stored in the storage means; and determining whether the operation expression data input by the expression input means by the determination means is equal to the storage means. more when it is determined that matches one of the operation data, the storage hand part of the answer obtained by the calculating means in response to the operation data stored in To the calculation result modification means for replacing the numerical data stored to correct as an accurate calculation result, the calculation formula data input by said input means a modified value as an accurate calculation result by the calculation result modification means Display means for displaying as an answer.
[0009]
That is, in the computer according to the present invention, the input arithmetic expression data is subjected to arithmetic processing and the arithmetic result is displayed. For example, a plurality of arithmetic data having a large number of numerical digits , such as a 2 ^m expression, and the respective arithmetic data are displayed . The numerical data of the lower n digits affected by the digit loss of the calculation result are stored in advance in association with each other, and the calculation formula data input by the formula input means matches any of the plurality of pre-stored calculation data. When it is determined that the calculation data is calculated, a part (lower n digits) of the answer obtained by the calculation means for performing the calculation of the calculation expression data is replaced with the previously stored numerical data corresponding to the calculation data. The result is corrected to the correct calculation result and displayed as the answer.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an electronic circuit of a computer according to an embodiment of the present invention.
[0011]
This computer has a CPU 11.
The CPU 11 activates a system program stored in advance in the ROM 13 in response to a key operation signal from the key input unit 12 and executes operation control of each circuit unit. , A ROM 13, a RAM 14, a display drive circuit 15, and a liquid crystal display unit 16.
[0012]
The key input unit 12 has a data input key 12a for inputting a desired expression such as an alphabetic character, a number, an operator key, etc. by a combination of variables, numerical values, operators, etc., and an operation input by the data input key 12a. An “EXE” key 12b and the like that are operated when executing arithmetic processing according to the formula are provided.
[0013]
In the ROM 13, a system program for controlling the entire operation of the computer is stored in advance, and sub-programs for various arithmetic controls are also stored in advance.
[0014]
The ROM 13 also stores search table data 13a and correction table data 13b in advance.
2A and 2B are diagrams showing the contents of table data stored in advance in the ROM 13 of the computer. FIG. 2A shows an example of search table data 13a, and FIG. 2B shows correction table data. It is a figure showing an example of 13b.
[0015]
In the search table data 13a, for example, a plurality of fixed arithmetic expressions of 2 ^m or more (m = 46 in the present embodiment) or more which are affected by a digit drop with a high frequency of use and a large number of numerical digits accompanying the calculation are included. It is stored in advance in association with each address.
[0016]
The correction table data 13b is associated with the individual addresses of the plurality of fixed-form expressions stored in the search table data 13a, and is associated with each of the lower-order four of the answers obtained by operating each of the formulas, which are affected by the digit loss. Digit numerical data is stored in advance.
[0017]
In the RAM 14, a display register 14a in which data to be displayed is written as drawing data thereof, and an arithmetic expression corresponding to the arithmetic data input in accordance with the operation of the data input key 12a in the key input unit 12, are searched in the ROM 13. Formula search flag register F which is set to "1" when retrieved from the search table data 13a, and the formula which is retrieved in the search table data 13a when this flag register F is set to "1" And a work area 14c for temporarily storing and holding data input and output in various arithmetic processing processes centered on the CPU 11.
[0018]
Next, the operation of the computer having the above configuration will be described.
FIG. 3 is a flowchart showing the arithmetic processing in the electronic computer.
4A and 4B are diagrams showing a calculation display operation accompanying the calculation process of “2 ⁴⁷ ” in the computer. FIG. 4A is a diagram showing an input display state of a calculation expression, and FIG. It is a figure showing a display state of a result.
[0019]
As shown in FIG. 4A, when the operation expression data “2 ⁴⁷ ” to be operated is input by operating the data input key 12a of the key input unit 12, the input operation expression data is stored in the display register 14a in the RAM 14. On the other hand, it is developed as display data and displayed on the liquid crystal display unit 16 via the display drive circuit 15 (steps S1 → S2, S3).
[0020]
Then, when the "EXE" key 12b of the key input unit 12 is operated to instruct the execution of the arithmetic expression data "2 ⁴⁷ " displayed as input, the same arithmetic operation data "2 ⁴⁷ " corresponding to the input arithmetic expression data "2 ⁴⁷ " is input. Is retrieved from a plurality of fixed formulas stored in advance in the search table data 13a (see FIG. 2A) in the ROM 13 (steps S4 → S5).
[0021]
Here, when the same operation expression corresponding to the operation expression data "2 ⁴⁷ " displayed by key input is searched from the search table data 13a, "1" is set in the operation expression search flag register F in the RAM 14. Is set, and the address No. “2” indicating the storage area of the retrieved arithmetic expression “2 ⁴⁷ ” is stored in the address No. register 14b in the RAM 14 (steps S6 → S7, S8).
[0022]
Then, the arithmetic processing in the CPU 11 is executed according to the input arithmetic expression data “2 ⁴⁷ ” (step S9).
In this case, in the arithmetic processing in the CPU 11, the number of digits that can be processed is limited in advance, so that numerical data having a large number of digits will lose digits, and the calculation result of “2 ⁴⁷ ” in the step S9 ( Answer) is calculated as “1407... 5325” that includes an error due to cancellation in the first lower digit.
[0023]
Thus, it is determined that “1” is set in the arithmetic expression search flag register F in the RAM 14 with the arithmetic result (answer) of the input arithmetic expression data “2 ⁴⁷ ” once calculated by the CPU 11. Then, the four-digit correction data "5328" stored in the correction table data 13b in the ROM 13 is read out according to the address No. "2" stored in the address No. register 14b in the RAM 14 (step). S10 → S11).
[0024]
Then, the correction data “5328” read from the correction table data 13b in the ROM 13 is compared with the calculation result (answer) “1407... 5325” of “2 ⁴⁷ ” already calculated in step S9. , Are substituted and replaced in the range of the lower four digits, and are corrected as an accurate calculation result (answer) of “2 ⁴⁷ ” “1407... 5328” (step S12).
[0025]
Then, the flag of the arithmetic expression search flag register F in the RAM 14 is reset to “0”, and it is determined that the arithmetic operation of the input expression “2 ⁴⁷ ” is completed. (Answer) "1407... 5328" is developed as display data in the display register 14a in the RAM 14, and displayed on the liquid crystal display unit 16 via the display drive circuit 15 as shown in FIG. 4B (step S13). , S14 → S3).
[0026]
As a result, the calculation result (answer) in which an error has occurred due to the effect of the digit loss accompanying the calculation processing in the CPU 11 is corrected by replacing the lower four digits with correct correction data, thereby obtaining an accurate calculation result (answer). You will be able to obtain.
[0027]
FIG. 5 is a diagram showing a calculation display operation associated with the calculation process of “2 ⁴⁷ -328” in the computer, and FIG. 5A is a diagram showing an input display state of a calculation expression, and FIG. FIG. 7 is a diagram showing a display state of a calculation result.
[0028]
In this case, in the arithmetic processing in FIG. 3, through the processing of steps S1 to S13, first, the arithmetic processing of “2 ⁴⁷ ” and the correction to the accurate arithmetic result (answer) “1407... 5328” are made. Then, when it is determined in step S14 that the calculation is not completed, the process returns to step S5 again.
[0029]
Then, after the processing of steps S5, S6 → S9, S10 → S14, "1407 ... 5328-328" that is computed, the process proceeds to step S3, calculation formula data ^"2 47 -328" and its exact The calculation result (answer) “1407... 5000” is displayed on the liquid crystal display unit 16.
[0030]
Therefore, according to the computer having the above configuration, when the operation formula data “2 ⁴⁷ ” is input by the data input key 12 a of the key input section 12 and the “EXE” key 12 b is operated, the arithmetic processing is started by the CPU 11. Then, after obtaining an operation result (answer) “1407... 5325” in which an error occurs in the lower first digit due to the digit loss, the operation stored in advance in the search table data 13a and the correction table data 13b in the ROM 13 is performed. Correction data “5328” for the lower four digits of the correct answer corresponding to the expression “2 ⁴⁷ ” is read out, the lower four digits of the answer obtained by the CPU 11 are replaced, and the correct answer is “1407... 5328”. Since the data is corrected and displayed on the liquid crystal display unit 16, the number of digits of numerical data to be processed in accordance with the calculation of the input expression is increased. Even if the number of digits that can be stored exceeds the maximum number of digits that can be processed by the CPU 11 and a calculation error occurs due to a digit loss, an accurate calculation result can be obtained as an answer.
[0031]
In this case, in the above-described embodiment, all digits of the answer of each of the fixed formulas are stored in the correction table data 13b in correspondence with the plurality of fixed formulas stored in the search table data 13a in the ROM 13. Instead of storing, only the lower n digits affected by the digit loss are stored, and after the arithmetic processing by the CPU 11, the lower n digits of the operation result (answer) are replaced with correction data to correct the value to an accurate value. Therefore, the memory capacity in the ROM 13 is not occupied significantly, and the correction data can be used efficiently.
[0032]
【The invention's effect】
As described above, according to the computer according to the present invention, which displays the operation result input arithmetic expression data processing to, for example, a plurality of operations numerical digits increases such 2 ^m Formula The data and the lower-order n-digit numerical data that are affected by the digit loss of the respective calculation results are stored in advance in association with each other, and the calculation formula data input by the formula input means is used to store the plurality of previously stored calculation data. If it is determined that any one of the following is true, a part (lower n digits) of the answer obtained by the calculating means for executing the operation of the operation expression data is stored in advance in correspondence with the operation data. The data is replaced with the calculated numerical data , corrected to the correct calculation result, and displayed as an answer.
Therefore, it is possible to provide an electronic computer capable of obtaining an accurate answer even when a digit is lost in the lower digit of the numerical data to be processed.
[Brief description of the drawings]
FIG. 1 is an exemplary block diagram showing the configuration of an electronic circuit of an electronic computer according to an embodiment of the present invention.
FIG. 2 is a diagram showing contents of table data stored in a ROM of the computer in advance, wherein FIG. 2A shows an example of search table data, and FIG. 2B shows correction table data; FIG.
FIG. 3 is a flowchart showing a calculation process in the computer.
4A and 4B are diagrams showing a calculation display operation accompanying the calculation process of “2 ⁴⁷ ” in the computer. FIG. 4A is a diagram showing an input display state of a calculation expression, and FIG. The figure which shows the display state of a calculation result.
5A and 5B are diagrams showing a calculation display operation accompanying the calculation process of “2 ⁴⁷ -328” in the computer. FIG. 5A is a diagram showing an input display state of a calculation expression, and FIG. () Is a diagram showing a display state of a calculation result.
6A and 6B are diagrams showing a calculation display operation accompanying the calculation process of “2 ⁴⁷ ” in a conventional computer. FIG. 6A is a diagram showing an input display state of a calculation expression, and FIG. 9 is a diagram showing a display state of a calculation result.
[Explanation of symbols]
11 ... CPU,
12 ... key input section,
12a Data input key,
12b ... "EXE" key,
13 ... ROM,
13a: table data for search,
13b: correction table data,
14 ... RAM,
14a: display register,
14b: Address No register,
14c ... work area,
F ... arithmetic expression search flag register,
15 Display drive circuit
16 Liquid crystal display unit.

Claims (2)

In an electronic calculator that performs arithmetic processing on input arithmetic expression data and displays an arithmetic result,
Expression input means for inputting operation expression data for performing the operation,
Calculating means for executing the calculation of the calculation formula data input by the formula input means;
Storage means for storing a plurality of predetermined operation data and numerical data in association with each other,
Determining means for determining whether or not the arithmetic expression data input by the expression input means matches any of the plurality of arithmetic data stored in the storage means ;
When the determining means determines that the arithmetic expression data input by the expression input means matches any of the plurality of arithmetic data stored in the storage means, one of the answers obtained by the arithmetic means is obtained. An operation result correction unit for replacing the unit with numerical data stored in the storage unit corresponding to the operation data and correcting the result as an accurate operation result ;
And display means causes the display as the answer of the input arithmetic expression data by the input unit the corrected value as an accurate calculation result by the calculation result correction means,
An electronic computer comprising: The numerical data storing means stores the electronic computer according to claim 1, wherein the numeric data corresponding to lower n digits of the answer obtained by the calculation means.

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