Formula Forensics No.004 – Fred’s Problem

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About 6 months ago, Fred asked a question on the Chandoo.org Forums: I need idea on a simpler formula

In column A I have the total sum product of C to AU
Line one has all the names.
A2 = (B2*C2)+(D2*E2)+(F2*G2)+(H2*I2)+(J2*K2)+(L2*M2)+…+(AT2*AU2)
A3 = (B3*C3)+(D3*E3)+(F3*G3)+…+(AT3*AU3)

Is there is simpler way by line to do this without clicking each cell on line 2?

I tried Sumproduct but I think I have received a wrong answer during testing.

 

Hui offered a Sumproduct Formula as a solution

=SUMPRODUCT((B2:AT2) * MOD(COLUMN(B2:AT2) -1, 2), (C2:AU2) * MOD(COLUMN(C2:AU2), 2))

and then followed up with a simpler Sumproduct Formula a day later

=SUMPRODUCT(B2:AT2 * C2:AU2 * (MOD(COLUMN(B2:AT2), 2) =0))

Let’s take a look at this second solution.

 

Setup the Problem

Copy the numbers 10,20 into alternate Cells A2:U2 or download the example file here: Example File (Excel 97-2010)

Copy this formula into B6: =SUMPRODUCT(B2:U2 * C2:V2 * (MOD(COLUMN(B2:U2), 2)=0))


Pull The Formula Apart

Lets take a look inside this formula and see how it works.

=SUMPRODUCT(B2:U2*C2:V2*(MOD(COLUMN(B2:U2),2)=0))

We can see that in the above formula the main function used in the formula is a Sumproduct Function.

=SUMPRODUCT(B2:U2*C2:V2*(MOD(COLUMN(B2:U2),2)=0))

Within the Sumproduct function there are 3 arrays, which are multiplied together

Array 1: B2:U2

Array 2: C2:V2

Array 3: (MOD(COLUMN(B2:U2),2)=0)

What’s in these arrays?

Array 1 is simply the range from B2:U2

Array 2 is simply the range from C2:V2, note that it is offset from the first array by 1 Column.

This is so that the first value of the Second Array matches the first value of the First Array. That is they are both in position 1 within there respective arrays.

Array 3 is where all the action is.

Enter  =(MOD(COLUMN(B2:U2),2)=0) into a cell and press F9

Excel returns: ={TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE}

Lets look at what is happening here

=(MOD(COLUMN(B2:U2),2)=0)

Mod returns the remainder of the first value Column(B2:U2) after dividing it by the second value 2.

Column(B2:U2) returns the Column Number for each cell in the Range B2:U2.

Because this part of the formula is in a Sumproduct formula it is evaluated as an Array Formula and hence it does this for each cell in the range B2:U2, thus returning an Array as the answer.

We can see that if we enter =MOD(COLUMN(B2:U2),2) into a cell and evaluate it with F9

={0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1}

However in this case we want to convert this from an array of Numbers to an array of True/False

A simple addition of an =0 does the trick

=(MOD(COLUMN(B2:U2),2)=0)

Now causes the formula to return: ={TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE}

So How does this go together with the other 2 arrays?

We now have 3 arrays:

Array 110,20,10,20,10,20,10,20,10,20,10,20,10,20,10,20,10,20,10

Array 220,10,20,10,20,10,20,10,20,10,20,10,20,10,20,10,20,10,20

Array 3: TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE

When Multiplying arrays, Excel multiplies the first value of each array and then the second value of each array, etc, effectively doing

={10*20*True, 20*10*False , 10*20*True, 20*10*False , 10*20*True, 20*10*False , 10*20*True, 20*10*False , 10*20*True, 20*10*False , 10*20*True, 20*10*False , 10*20*True, 20*10*False , 10*20*True, 20*10*False , 10*20*True, 20*10*False , 10*20*True}

You can see above that when the 3 arrays are multiplied it will only be the Odd entries in Arrays 1 & 2 which are evaluated by the Sumproduct, as all the even entries are multiplied by False which is equivalent to Zero

So the above evaluates to

={200,0, 200,0, 200,0, 200,0, 200,0, 200,0, 200,0, 200,0, 200,0, 200}

Sumproduct then takes over and adds the values together returning, 2000, the correct answer.

 

Problem Extension

After solving the problem, Fred decided to add a column between each entry in the data set.

The solution is posted in the forum and is also shown in the example file.

You can work through that formula at your leisure, except to say that it is similar to the solution above.

Alternate Solution

Luke correctly pointed out that the data was poorly arranged and the solution would be much simpler had the data been more logically arranged.

However as an Excel practioner we are often called to solve other peoples dirty work.

 

HINTS

You will notice that in the solution of this problem I have done a few small things that make solving the problem easier.

Use Smaller Subsets of the Data.

Instead of putting numbers from Columns B to AU as Fred has I have used a set from Column B to U.

This way I can see all the data on one Excel screen without scrolling as well as the formula links and extents when pressing F2 on the cell containing the formula.

Use Simple Numbers

Use numbers that you can manually check. In this example I can easily, manually, check that the answer should be 2000.

Evaluate

Where ever possible, enter sections of a formula in a cell and evaluate its output:

=(MOD(COLUMN(B2:U2),2)=0) and press F9

={TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE,TRUE,FALSE}

See how easily we can check that this section is returning the correct values.

 

OTHER POSTS IN THIS SERIES:

You can learn more how to pull Excel Formulas apart in the following posts:

http://chandoo.org/wp/category/formula-forensics/

The link above, will show you all the posts in this series

 

WHAT FORMULAS WOULD YOU LIKE EXAMINED?

If you have any formulas you would like explained please feel free to leave a post here or send me an email:

If the formula is already on Chandoo.org or Chandoo.org/Forums, simply send the link to the post and a Comment number if appropriate.

If sending emails please attach an Excel file with the formula and data

 

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26 Responses to “Get busy this weekend, with OR XOR AND [Excel Homework]”

  1. Stef@n says:

    first solution for AND
    The two numbers are in A1 and B1
    = SUBSTITUTE (SUBSTITUTE (A1+B1*9*9, 9, 1), 8, 0)
    regards
    Stef@n

  2. Stef@n says:

    next solution for OR
    =1*SUBSTITUTE (A1+A2;2;1)

    regards
    Stef@n

  3. Stef@n says:

    last solution for XOR
    =1*SUBSTITUTE (A1+A2;2;0)

    regards
    Stef@n

  4. Irvine says:

    Or you could make use of the VBA logical operators!

    Define the following as custom functions
    Public Function BITXOR(x As Long, y As Long)
    BITXOR = x Xor y
    End Function

    Public Function BITAND(x As Long, y As Long)
    BITAND = x And y
    End Function

    Public Function BITOR(x As Long, y As Long)
    BITOR = x Or y
    End Function

    and then use them such:
    A B =BITOR(A,B) =BITAND(A,B) =BITXOR(A,B)
    0101 0100 0101 0100 0001

  5. Stef@n says:

    an another solution for AND
    =1*SUBSTITUTE (SUBSTITUTE (A1+A2;1;0);2;1)

    note:
    the binary numbers are in A1 and A2 !
    regards
    Stef@n

  6. Shair says:

    I was obviously playing hooky at the beach during the bit-wise math lesson – you lost me at “Understanding bit-wise operations” 🙂

  7. Anup Agarwal says:

    After looking at the above solutions, I find my solution silly, but still:

    For the following formulae,
    Row 1: headers,
    Row 2: OR
    Row 3: AND
    Row 4: XOR

    Column 1: Input 1
    Column 2: Input 2
    Column 3: Result

    OR
    {=SUM(IF(MID(A2,ROW(OFFSET($A$1,0,0,LEN(A2),1)),1)+MID(B2,ROW(OFFSET($A$1,0,0,LEN(B2),1)),1)>0,1,0)*10^(LEN(A2)-ROW(OFFSET($A$1,0,0,LEN(B2),1))))}

    AND
    {=SUM(IF(MID(A3,ROW(OFFSET($A$1,0,0,LEN(A3),1)),1)+MID(B3,ROW(OFFSET($A$1,0,0,LEN(B3),1)),1)=2,1,0)*10^(LEN(A3)-ROW(OFFSET($A$1,0,0,LEN(B3),1))))}

    XOR
    {=SUM(IF(MID(A4,ROW(OFFSET($A$1,0,0,LEN(A4),1)),1)+MID(B4,ROW(OFFSET($A$1,0,0,LEN(B4),1)),1)=1,1,0)*10^(LEN(A4)-ROW(OFFSET($A$1,0,0,LEN(B4),1))))}

  8. Hui... says:

    @Anup
    Please don't consider your solution silly
    Firstly, You are the 3rd person to submit an answer
    Secondly, The best formula/function is the one that you know and understand.

  9. Michael Azer says:

    I think I have a very tedious solution, which people won't have the patience to do except in small numbers.

    I used the same problem setup as "Anup Agarwal"

    AND =IF(AND(MID(B2,1,1)="1",MID(C2,1,1)="1"),1,0)&IF(AND(MID(B2,2,1)="1",MID(C2,2,1)="1"),1,0)&IF(AND(MID(B2,3,1)="1",MID(C2,3,1)="1"),1,0)&IF(AND(MID(B2,4,1)="1",MID(C2,4,1)="1"),1,0)

    OR =IF(OR(MID(B3,1,1)="1",MID(C3,1,1)="1"),1,0)&IF(OR(MID(B3,2,1)="1",MID(C3,2,1)="1"),1,0)&IF(OR(MID(B3,3,1)="1",MID(C3,3,1)="1"),1,0)&IF(OR(MID(B3,4,1)="1",MID(C3,4,1)="1"),1,0)

    =IF(OR(AND(MID(B4,1,1)="1",MID(C4,1,1)="0"),AND(MID(B4,1,1)="0",MID(C4,1,1)="1")),1,0)&IF(OR(AND(MID(B4,2,1)="1",MID(C4,2,1)="0"),AND(MID(B4,2,1)="0",MID(C4,2,1)="1")),1,0)&IF(OR(AND(MID(B4,3,1)="1",MID(C4,3,1)="0"),AND(MID(B4,3,1)="0",MID(C4,3,1)="1")),1,0)&IF(OR(AND(MID(B4,4,1)="1",MID(C4,4,1)="0"),AND(MID(B4,4,1)="0",MID(C4,4,1)="1")),1,0)

  10. Michael Azer says:

    Sorry my last post was totally messed up

    AND
    =IF(AND(MID(B2,1,1)="1",MID(C2,1,1)="1"),1,0)&IF(AND(MID(B2,2,1)="1",MID(C2,2,1)="1"),1,0)&IF(AND(MID(B2,3,1)="1",MID(C2,3,1)="1"),1,0)&IF(AND(MID(B2,4,1)="1",MID(C2,4,1)="1"),1,0)
    OR
    =IF(OR(MID(B3,1,1)="1",MID(C3,1,1)="1"),1,0)&IF(OR(MID(B3,2,1)="1",MID(C3,2,1)="1"),1,0)&IF(OR(MID(B3,3,1)="1",MID(C3,3,1)="1"),1,0)&IF(OR(MID(B3,4,1)="1",MID(C3,4,1)="1"),1,0)
    XOR
    =IF(OR(AND(MID(B4,1,1)="1",MID(C4,1,1)="0"),AND(MID(B4,1,1)="0",MID(C4,1,1)="1")),1,0)&IF(OR(AND(MID(B4,2,1)="1",MID(C4,2,1)="0"),AND(MID(B4,2,1)="0",MID(C4,2,1)="1")),1,0)&IF(OR(AND(MID(B4,3,1)="1",MID(C4,3,1)="0"),AND(MID(B4,3,1)="0",MID(C4,3,1)="1")),1,0)&IF(OR(AND(MID(B4,4,1)="1",MID(C4,4,1)="0"),AND(MID(B4,4,1)="0",MID(C4,4,1)="1")),1,0)

  11. Stephen says:

    @stefan,
    I just couldn't get your solutions to work.
    01010101010 + 01010101110 = 02020210120
    what am i doing wrong?

  12. Stephen says:

    @anup
    ...I got yours to work!

  13. Rich says:

    @Stephen - I get the same, but Stef@an's second solution for AND does work (at least for the test cases I used)

  14. Stef@n says:

    @ Stephen / Rich
    yes , you are right ! - only this works:

    OR
    =1*SUBSTITUTE (A1+A2;2;1)
    XOR
    =1*SUBSTITUTE (A1+A2;2;0)
    AND
    =1*SUBSTITUTE (SUBSTITUTE (A1+A2;1;0);2;1)

  15. Michael Azer says:

    @Stef@n - You're answer is really smart, I never knew about the substitute function before. Great Work!

  16. Stef@n says:

    Thx Michael 🙂
    yes - it is simply easy 😉
    if you add 1 and 1 - excel calculate 2
    and then you have to substitute the 2 - new = 0 respectively 1

  17. Rob says:

    Here is a good resource for people wanting to learn binary and hexadecimal.
    http://justwebware.com/bitwise/bitwise.html

  18. Kyle McGhee says:

    Three that weren't asked for:
    NOT
    =SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A1+A2,0,3),1,0),3,1)

    EQV
    =SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A1+A2,0,3),2,3),1,0),3,1)

    IMP
    =SUBSTITUTE(SUBSTITUTE(A1+SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A2,0,3),1,0),3,1),0,1),2,0)

    (was using Daniel Ferry's bitwise file to verify against)

  19. Q says:

    @ Kyle

    Not only takes one parameter and inverts 0 -1 and 1-0

    Took out the +A2
    =SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A1,0,3),1,0),3,1)

  20. Great solutions!

    I'll add two:

    NAND =1*SUBSTITUTE (A1+A2,2,0)

    NOR=1*SUBSTITUTE(SUBSTITUTE (SUBSTITUTE(A1+A2,0,2),1,0),2,1)

  21. John Fuller says:

    This will work for binary numbers of any size (although the text format mask will have to have as many zeroes as there are digits in the longest addend)

    Assume binary #s are in C35 & C36, then add and format as text in C37:
    =TEXT(C36+C35,"000000000000")
    -sum- = 101112211112

    AND - SUBSTITUTE 0s for 1s in -sum-, then sub 1s for 2s
    =SUBSTITUTE(SUBSTITUTE(C37,"1","0"),"2","1")

    OR - sub 1s for 2s in -sum-
    =SUBSTITUTE(C37,"2","1")

    XOR - sub 0s for 2s in -sum-
    =SUBSTITUTE(C37,"2","0")

  22. Shane says:

    Just wandered by:

    AND:

    =SUBSTITUTE(A1+A2,1,0)/2

  23. Ronald Vonk says:

    Hi Chandoo,

    I am not (yet) really into bitwise calculation, but I am looking for a way to speed up my vba calculation with very big numbers. Would is ben convenient to use bitwise notation for this?

    Best regards,

    Ronald (the Netherlands)
    p.s. love your country!

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