CA1173164A - Fraction calculator - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A fraction calculator is disclosed which comprises key input part for input of fractional and decimal data, ROM
for storing therein a control program for decimal - fraction conversion, instruction keys for giving an instruction to execute the decimal - fraction conversion, operation control and processing unit for executing an operation for the decimal - fraction conversion in accordance with the program stored in the ROM and display device for displaying the input fractional and decimal data and the fractional data obtained by the processing unit.

Description

117316~

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Fraction Calculator BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to a fra~tion calculator and more particularly to a miniaturized electronic fraction calculator which enables to put in fractional data and also to convert units between different systems of unit.

Description of the Prior Art An example of unit of length is "inch". In the case of this unit "inch", a fractional expression such as "l/4 inch"
is frequently and customarily used. However, denominators commonly used for such fractional expression are limited only to six numbers, 64, 32, 16, 8, 4 and 2. Addition, subtraction, multiplication and division in such unit for which a fractional expression is the common practice, need very complicated calculations. The same applies to unit conversion, for example inch - meter conversion. Even when a common electronic compute~

is used for such calculations, there are often cause~ errors because of the fractional expression.

SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention ~5 to provide a fraction calculator which is able to perform :1~ 73164 arithmetic operations in such unit for which a fractional expression must be used as a rule, and also able to convert at once such unit into another unit.
It is another object of the invention to provide a fraction calculator which enables one to carry out calcula-tions between different units by very simple key operations at will and also to make a display of the result of the calculation in the form of a most easily understandable fraction.
In accordance with the present invention there is provided a fraction calculator comprising input means for input of fraction data and decimal data; memory means having a control program stored therein for converting said decimal data into fraction data; instruction means for giving an instruction to convert said decimal data into fraction data; operation control and processing means for performing the operation for conversion of said decimal data into fraction data in response to the instruction given by said instruction means and in accordance with the control program stored in said memory means; and display means for displaying the input fraction data and decimal data from said input means as well as the data fractionized by said operation control and processing means.
Other and further objects, features and advantages of the invention will appear more fully from the following description taken in connection with the accompanying drawings.

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BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a plan view of a fraction calculator showing an embodiment of the invention;
Fig. 2 is a block diagram of control circuit showing the structure of the calculator shown in Fig. l;
Figs. 3A and 3B are control flow chart of the fraction calculator according to the invention; and Fig. 4 is a control flow chart for a decimal -fraction conversion.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to Figure 1 showing an embodiment of the present invention, the fraction calculator includes a - 2a -ï:~7316~

1 display l provided on a part of the apparatus. On the display l either of fractional number and decimal number can be display-ed. As an example, a fractional number of 3372 has been shown on the display l of this embodiment. Designated generally by 2 are keys such as input numeral keys and operation keys.
Among these keys, key 6 is a fraction key provided with a punctuation mark to be used in a mixed fraction and between denominator and numerator or for other similar purposes.
4 and 5 are conversion instruction keys provided with arrows which indicate the direction in which a conversion of unit should be carried out between two different units. The directions of arrows correspond to the directions indicated by unit display conversion instruction marks 3 on the respectiv~
keys. 7 is a power source switch, 8 is a mixed fraction display mark and 9 is a fraction display mark.

The manner of operation of the fraction calculator with the above shown key arrangement will be described in connection with an example where 22.l mm + 4 inch is calculated and the result is given in inch.

In this case, the operation proceeds in the following sequence shown in Table l.

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1 Table 1 OperationDisplay Step in ~ mm 0.03937 h 0.870077 c ~ ~ 0.7~75 d ~ ~ ~ 1~ 4 f 1 - 1~ 8 h At the step a, an instruction is given to execute the conversion of in ~ mm in the direction of arrow going leftward so as ko make a display of the value in inch corresponding to 1 mm. At the step _, there is displayed 1 mm = 0.03937 in.
At the step c, the value is multiplied by 22.1. The result is that 22.1 mm = 0.870077 in. These operations are equivalent to the sequential key operation of Q, ~, ~, ~, ~, ln ~ mm depressed in this sequence.
At the step d, an instruction for conversion to fraction is given. The result obtained is 7/8. By depressing key ~ at the step e there is displayed 0.875. This displayed

2~ value is slightly different from the value given at the previouc ~ 3~

1 step c because of a fractional error. Such fractional error results from the fact that the value obtained at the step c is fractionized by use of the minimum fractional unit, 1/64 in inch.
At the step f, 1/4 in. is added and the result is 1. 125 which is shown at the step g The addition is carried out after converting the input 1/4 in. into the corresponding decimal. At the last step _, the result of addition is convert-ed from decimal to fraction. Thus, there is obtained 118 inch which is the closest approximation of the true value in inch resulting from the calculation of 22.1 mm + 4 inch.
The manner how to convert decimal data into fractional data will be described.
As previously noted, in the case of fractional expres-sion of inch there are used 64, 32, 16, 8, 4, 2 as denominators This is equivalent to the use of 1/64 as the fractional minimum unit in inch. Therefore, let X be a given value, Y be its integer part and Z be its decimal part. Then, the given value X can be expressed as follows.
O X = Y + Z x 64/64.
Round off the operational result of Z x 64 to the first place of the integer and let the rounded value be Z'.
Then, ~' which is the closest approximation of X in fractional expression, is given by : X' = Y + Z'/64.
When Z' is an even number it is required to divide the denominator and numerator by 2 for a reduction of the fraction.

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1 This reduction of fraction is repeated until the numerator becomes an odd number.
By way of example a detailed description will be made of the calculation from step c to step d in the above Table 1.
In this case, the decimal data, X = 0.870077. The integer part Y is 0(zero). Therefore, X = Y = 0.870077.
Z x 64 = 55.684928. From it Z' = 56 and X' = 56/64. In the resulting fraction 56/64, both of the denominator and the numerator are even numbers. Therefore, the fraction is reduced by dividing the denominator and numerator by 2 until the latter becomes an odd number. Finally, there is obtained the desired simple fraction, X' = 7/8.
Figure 2 is a block diagram showing the structure of the fraction calculator according to the invention.
In Figure 2, the reference numeral 11 depicts a key input part. Data input is effected by depressing keys shown in Figure 1. 13 is a processing unit for carrying out necessary operational processing in accordance with the input data from the key input part 11 and performing other control functions.
~0 All the processing and controlling operations of the processing unit 13 are controlled in accordance with a program stored in ROM 16. 12 is a decimal ~ fraction converter. If the input data from the key input part 11 and/or the resulting data from the processing unit are decimal, the converter 12 converts the decimal data into data in the form of fraction. This decimal 117316q 1 ~ fraction converter 12 is also controlled in accordance with a decimal -~ fraction converting program stored in the ROM 16.
14 is a fraction -~ decimal converter in which the input frac-tion data from the key input part 11 and/or the processed data from the decimal ~ fraction converter 12 are converted into decimal data. This conversion process is carried out in accordance with a division program conventionally used in a common calculator. 15 is a display device for displaying the input numerical data (including fractional data and decimal data) from the key input part 11, the processed data from the processing unit 13, the fractional data from the decimal fraction converter 12, the decimal data from the fraction decimal converter 14 etc.
The above mentioned processing unit 13 includes therein flag S18, flag AR 20 and 1ag AL 19. When the fraction key 6 in the key input part 11 is depressed and a key signal corresponding to the fraction key 6 is issued, the flag S18 is set to indicate the depression of the fraction key 6. Similar-ly, the flag AR 20 indicates the depression of the conversion 2() instruction key 4 and the flag AL 19 indicates the depression of the conversion instruction key 5. The processing unit 13 further includes registers for storing the input data from the key input part 11, the operation processed data and other data from various processing steps.
The manner of operation of the above fraction calculato 1:~7316~

1 will be now described in connection with the case wherein 22.1 mm +l4 in. is to be calculated (the sequential operations thereof have been shown in Table 1) and with reference to the control flow chart shown in Figures3A and 3B.
At the first step Sl, the operator depresses ~ key at the key input part 11 to put out a key signal corresponding to the depressed key. The key signal is introduced into the processing unit 13 which discriminates the key just now depressed. In this case, the depressed key is ~ key and therefore the step is advanced in the sequence of step S2 -~
step S3 t step S4 -~ step S14 t step S20~ At the step S20, the data rl~ is stored in a register not shown. At the next step S13, the numerical data rlJ is displayed.
Subseqnently, the operator depresses the conversion instruction key 5, that is, ~ key in the key input part 11 to produce a key signal corresponding to ~ key. The output key signal is introduced into the processing unit 13 which discriminates the depressed key. Since the depressed key is ~ key, the step flows in the sequence of step Sl -~ step S2 t step S3 ~ step Sl9. At the step Sl9, the flag AL 19 is set to indicate that the conversion instruction key 4 has been depressed. The above sequence of key operations and the state of the display resulting therefrom are shown at step _ in Table 1.
By operator's depressing ~ key in the key input part 11~316~

1 ll subsequent to the above, a key signal corresponding to the depressed key is introduced into the processing unit 13 which discriminates the depressed key. As the key now depressed is ~ key, the step flows in the sequence of step S1 ~ step S2 -~
Step S3 ~ step S4 -~ step S5. At the step S5, a discrimination is made as to whether or not the depressed key is a specific key. For the fraction computer according to the present invention, ~ key, ~ key and the like are defined as specific keys. Therefore, at the step S5, the depressed key ~ is judged to be a specific key and the step is advanced to step S6. At the step S6, it is judged whether or not the flag S18 has been set to indicate that the fraction key ~ has been depressed so far. Under the position now being discussed, ~ key is in its reset position because it has never been depressed yet. Therefore, the step is advanced to step S9.
At the step S9, a discrimination is made as to which unit conversion key has been depressed. In the case now being discussed, the key is the unit conversion key 4 and the flag AL 19 is in its set position to indicate that the conversion key 4 has been depressed. Therefore, the step is advanced to step Sll at which a conversion operation is performed for mm ~ inch unit conversion. Namely, a calculation is carried out to obtain the value in inch corresponding to one milimeter.
At the next step S12, the flag ALl9 is reset and the value obtained by the unit conversion operation at the step Sll is 117316~

1 display. These key operations and the state of display result-ing therefrom are shown at the step _ in Table 1.
Subsequently to the above, ~ key is depressed at the key input part 11 to produce a key signal corresponding to the key. The key signal is introduced into the processing unit 13 which discriminates the key now depressed. Therefore, the step goes on in the sequence of step Sl ~ step S2 ~ stepS3-step S14 ~ step S15. At the step S15, a discrimination is made as to whether or not ~ key has already been depressed.
This discrimination is effected by discriminating the position of the flag S18 which is set when ~ key is depressed. Under the condition now being discussed, the flag S18 is not in the set position. Therefore, the step is advanced to step S18.
This step S18 is a step where ordinary four fundamental arithmetic operations are carried out. However, since the calculator is now in the state of "0.03937 x", no arithmetic operation is performed at this step. Consequently, the display at step S13 remains in the state of "0.03937". When the next key input of ~ ~ ~ ~ is carried out, the step flows in the same manner as described above when ~ key was : depressed. Therefore, the state of the display at step S13 changes from "0.03937" to "22.1". Subsequently, ~ key is depressed to produce a key signal corresponding to the key.
The key signal is introduced into the processing unit 13 which 2~ makes the step flow in the same sequence as that when ~ key ' - 10 117316 ~

1 was depressed. But, at this time, an arithmetic operation of "0.03937 x 22.1" is performed at the step S18. The result of this operation, "0.870077" is displayed at step Sl3.
Thereafter, the unit conversion key 4, namely ~ key is depressed at the key input part 11 to put out a key signal corresponding to the unit conversion key. This key signal is applied to the processing unit 13 which discriminates the depressed key. Then, the step goes on in the sequence of step Sl ~ step S2 -~ step S3 ~ step Sl9. At the step Sl9, flag AR20 is set to indicate that the unit conversion key ~ has now been depressed. Upon the next keying of the fraction key 6, namely ~ key, a key signal corresponding to the key is introduced into the processing unit 13. The processing unit 13 discriminates the now depressed key ~ and makes the step flow in the sequence of step Sl ~ step S2 ~ step S21. At the step S21, a discrimination is made as to whether or not either flag AR20 or flag ALl9 has been set. Since flag AR20 has been set in this case, the step is advanced to step S22.
At the step S22, a discrimination is made as to whether or not the fraction key ~ has been depressed so far and the flag S18 is in its set position to indicate it. This discrimination is carried out only when the depression of the fraction key now done has been confirmed at the step S2. Since the flag S18 is not in its set position at this time, the step is 2~ advanced to step S25. At this step S25, the decimal data 11'7316~
"0.870077" obtained by the previous operation is converted into fractional data in accordance with the decimal - fraction conversion program stored in ROM 16. At the next step S26, flag S18 is set and at step S27 flag AR 20 is reset. The fraction data "7/8" obtained by the conversion at the step S25 is now displayed at step S13. These key operations and the state of display resulting therefrom are shown at step d in Table 1.
Subsequently to the above, the operator depresses E3 key at the key input part 11 to produce a key signal corres-ponding to the key. This key signal is introduced into the processing unit 13 which discriminates the depressed key.
Therefore, the flow of step goes in the sequence of step Sl step S2 ~ step S3 ~ step S4 ~ step S14. At the step S14 a discrimination is made as to whether or not the depressed~key is a function key. As it is a function key, the step is advanced to the next step S15. At this step S15 it is discriminated that the flag S18 is now in its set position.
The flag S18 is reset at the next step S16. At step S17, the fraction data "7/8" is converted into decimal data. At the next step S18 no operational processing is carried out in this case. The decimal data "0.875" obtained by the conversion operation at step S17 is displayed at step S13. These key operations and the state of display resulting therefrom are shown at step e in Table 1.

,~

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1 Upon the next key input by ~ key in the key input part 11, a key signal corresponding to the key is put into the processing unit 13. In the same sequence as the provious key input by the same key, the step is advanced and the input data "1" is stored in the register 17 at step S20 and displayed at step S13. When the next key ~ is depressed, the step is advanced in the sequence of step Sl ~ step S2 ~ step S21.
At the step S21 it is discriminated that neither flag AR20 nor flag AL 19 is set. Therefore, the step is advanced to step S28 at which the numerical data in the lowest place of the register 17 is shifted leftward and the fraction mark is loaded At the next step S29, the flag S18 is set and "1/" is displayed at step S13. The next key input by ~ key brings the same flow of step as above and "1/4" is displayed at step S13.

These key operations and the state of display resulting there-from correspond to those shown at step f in Table 1.
Subsequently, ~ key is depressed to produce a key signa corresponding to the key. The key signal is introduced into the processing unit 13 which discriminates the depressed key.

~0 Then, the step goes on in the sequence of step Sl ~ step S2 step S3 ~ step S4 ~ step S14. At the step S14, the key now depressed is judged to be a function key. Therefore,the step is advanced to step S15 at which a discrimination is made as to whether or not the flag S18 is in its set position. As the flag S18 is in its set position at this time, the step is 1 advanced to step S16 at which the flag S18 is reset. At the next step S17, the fraction data "1/4" is converted into decimal data. The result of this conversion operation is "0.25". This decimal data "0.25" and the previously obtained decimal data "0.875" are added together at the next step S18.
The result of this operation, that is, "1.125" is displayed at step S13. These key operations and the state of display resulting therefrom are shown at step g in Table 1.
Thereafter, the unit conversion key 4, namely ~ key is depressed to put a key signal corresponding to the key into the processing unit 13. The processing unit discriminates the now depressed key and makes a flow of step through step Sl step S2 ~ step S3. At the step S3, the now depressed key is judged to be a function key. Therefore, the step is advanced ~- 15 to step S20 at which the flag AR20 is set to indicate that the unit conversion key ~ has now been depressed. Subsequently, the fraction key 6, namely ~ key is depressed and a key signal corresponding to it is put into the processing unit 13.
The processing unit discriminates the depressed key and there-fore the step is advanced in the sequence of step Sl ~ step S2 ~ step S21. At the step S21, a discrimination is made as to whether or not flag AR20 or flag ALl9 is set. As the flag AR20 is in its set position in this case, the step is advanced to the next step S22. At the step S22, a discrimination is made as to whether or not flag S18 is in its set position to ' 1~73~fi~

1 indicate the depression of ~ key prior to the discrimination of the depressed 0 key at step S2. In this case, the flag S18 is not in the set position and therefore the step is advanced to step S25. At this step S25, the decimal data "1.125" obtained by the previous operation is converted into fraction data. At step S27, flag AR20 is reset. Th~ fraction data "18" resulting from the conversion operation at step S25 is displayed at step S13. These key operations and the state of display resulting therefrom are shown at step _ in Table 1.
In the manner described above, a calculation of "22.1mm + l4 inch" is performed and the result of this calculation is displayed in the form of fraction in inch.
Now the procedure of the decimal ~ fraction conversion executed at step S25 will be described in connection with the above decimal data "0.870077" and with reference to the control flow chart shown in Figure 4.
In this example, X = 0.870077. At the first step S41, the given decimal data is separated into integer part Y and decimal part Z. In this case, Y = 0 and Z = 0.870077. At ~0 the next step S42~ the minimum unit l/p is set. The minimum unit l/p is determined by the processing unit 13 when any desired one of the unit conversion instruction keys 4 and 5 is depressed and a key signal corresponding to the depressed unit conversion instruction key is introduced into the proces-sing unit. In the case of this example, p = 64 . At step S43, 11~3164 an operation z x p is executed. More concretely, there is executed an operation for "0.870077 x 64" At step S44, the operational result of Z x P in the abo~Te operation is rounded off to the first place of the integer. Since 0.870077 x 64 =
55.684928, the rounded value of Z x P is 56. At the next step S45, Pl and P2 are set providing that ZpP = p2 In the case of this example, Pl = 64 and P2 = 56 providing that 0.870077 x 64 = 566 . At step S46, Xl = P2 and Yl Pl a e concretely, Xl = 56 and Yl = 64 are set. At the next step S47, Xl = S is set. In the case of this example, S = 56. At step S 48, an operation " Yl . Xl" is executed to set Xl for the remainder of Xl . In the case of this example, an operation of 64 . 56 is executed and the remainder 8 is set as Xl.
At step S49, a discrimination is made as to whether the value of Xl set at the previous step is 0 or not. As Xl = 8 at the step S49, the step is advanced to step S50. At this step S50, Yl is set to S previously determined at step S47. From S = 56, Yl is set to 56. After setting Yl = 56, the step is shifted to step S47 at which S is set to 8(S = 8). At the next step S48, there is executed an operation "56 . 8" (wherein S = 8 and Yl = 56). At step S49 it is discriminated that the remainder of the above operation "56 . 8" is 0. Therefore, the step is advanced to step S51. At this step S51, Pl and P2 set at step S44 are divided by S finally set at the latest step S47. The values obtained by this operation of divisions, 117316~

1 S and S become the denominator and numerator of the fraction resulting from the decimal ~ fraction conversion. In the case of this example, since S = 8, Pl = 64 and P2 = 54~ Pl = Sl is 8 and P2 = S is 7. Thus, the conversion of the given decimal data " 0.870077" lnto fraction data gives "78"
While a calculation example and a conversion example have been particularly shown and described in connection with a unit conversion between inch and milimeter, it should be understood that the above description is applicable also to other unit conversions between feet and meter, between mile and kilometer and the like. The conversion instructions for these unit conversions are marked on the respective input keys 2 as shown in Figure 1.

Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A fraction calculator comprising:
input means for input of fraction data and decimal data;
memory means having a control program stored therein for converting said decimal data into fraction data;
instruction means for giving an instruction to convert said decimal data into fraction data;
operation control and processing means for performing the operation for conversion of said decimal data into fraction data in response to the instruction given by said instruction means and in accordance with the control program stored in said memory means; and display means for displaying the input fraction data and decimal data from said input means as well as the data frac-tionized by said operation control and processing means.

2. A fraction calculator as set forth in Claim 1, wherei said memory means has a control program stored therein for converting the input fraction data from said input means into decimal data.

3. A fraction calculator as set forth in Claim 1, where-in said input means includes a fraction key for indicating the punctuation between numerator data and denominator data.

4. A fraction calculator as set forth in Claim 1 wherein, when the fraction data displayed by said dispaly means is a mixed fraction, said display means displays also a mixed fraction mark to indicate that said displayed fraction data is a mixed fraction.

5. A fraction calculator comprising:
input means for input of fraction data and decimal data;
unit conversion instruction means for giving an instruc-tion to convert the unit of the input fraction data and decimal data from said input means into another unit;
memory means having a control program stored therein for converting said decimal data into fraction data;
decimal ? fraction conversion instruction means for giving an instruction to convert said decimal data into fraction data;
operation control and processing means for determining the minimum value in the form of fraction in accordance with the instruction given by said unit conversion instruction means and performing the operation for decimal ? fraction conversion in response to the instruction given by said decimal ? fraction conversion instruction means and in accord-ance with the control program stored in said memory means; and display means for displaying the input fraction data and decimal data from said input means as well as the data fractionized by said operation control and processing means.

6. A fraction calculator as set forth in Claim 5, wherein said input means includes a fraction key to indicate the punctuation between numerator data and denominator data.

7 A fraction calculator as set forth in Claim 5, wherein said memory means has also data of the fractional minimum value stored therein to be determined by said operation control and processing means.