SUMPRODUCT Question

[Victor Chapman]

This maybe a strange question, but I have a SUMPRODUCT function that
works in Excel, however, I don't understand why it does.

Here is what I have:

An array of task times (Duration) B3:B41

A matrix of names of people assigned to the various tasks throughout the
week (WEEK)D3:H41 (The names appear one or more times)

The array of individual names appears in A43:A61

Now I want to know the total time each individual spends carrying out
one or more of the tasks. This is done with:

SUMPRODUCT((WEEK=$A43) * Duration)

This function appears beside each name with the row number incremented
accordingly. IT WORKS!

Here is my problem, I can't find anywhere in the documentation for this
function (or another example) where a row number in a matrix will look
up the corresponding row number in an array. So I don't understand why
it provides the desired result.

I would appreciate more examples of this use of SUMPRODUCT and technical
explanation of why it works.

TIA



--

_______________________________
Regards,
Vic Chapman

[Biff]

Hi!

(WEEK=$A43) will return an array of boolean TRUE or FALSE. Something like
this:

D3 = A43 = TRUE
D4 = A43 = FALSE
D5 = A43 = TRUE
D6 = A43 = FALSE

Then those boolean values are multiplied by the corresponding duration
values from the other array, B3:B41. That would look like this:

TRUE * B3 = B3
FALSE * B4 = 0
TRUE * B5 = B5
FALSE * B6 = 0

Then the values are summed together and you get your result.

There's a very detailed explanation of Sumproduct here:

http://www.xldynamic.com/source/xld.SUMPRODUCT.html

Biff

"Victor Chapman" <[email protected]> wrote in message
news:[email protected]...
> This maybe a strange question, but I have a SUMPRODUCT function that works
> in Excel, however, I don't understand why it does.
>
> Here is what I have:
>
> An array of task times (Duration) B3:B41
>
> A matrix of names of people assigned to the various tasks throughout the
> week (WEEK)D3:H41 (The names appear one or more times)
>
> The array of individual names appears in A43:A61
>
> Now I want to know the total time each individual spends carrying out one
> or more of the tasks. This is done with:
>
> SUMPRODUCT((WEEK=$A43) * Duration)
>
> This function appears beside each name with the row number incremented
> accordingly. IT WORKS!
>
> Here is my problem, I can't find anywhere in the documentation for this
> function (or another example) where a row number in a matrix will look up
> the corresponding row number in an array. So I don't understand why it
> provides the desired result.
>
> I would appreciate more examples of this use of SUMPRODUCT and technical
> explanation of why it works.
>
> TIA
>
>
>
> --
>
> _______________________________
> Regards,
> Vic Chapman

[JulieD]

Hi Victor

Probably the best reference for information on the sumproduct function that
i know about is at

http://www.xldynamic.com/source/xld.SUMPRODUCT.html

But basically the sumproduct function works by evaluation true statements to
1 and false statements to 0 ...

For a quick overview of your sumproduct funtion look at it this way:
=SUMPRODUCT((WEEK=$A43) * Duration)
=SUMPRODUCT((D3:H41 =$A43)*B3:B41)
(for this example i'm make the ranges smaller .... e.g.)
=SUMPRODUCT((D1:F3 =$G1)*B1:B3)
(and use the following data)
.......A........B.........C.........D........E.........F.............G
1.............10...................Bill......Fred....Steve.......Anne
2.............15...................Anne...Bill.......Fred........Bill
3.............20...................Fred....Anne....Steve......Steve

In G2 the SUMPRODUCT formula would work like this
=SUMPRODUCT((D1:F3 =$G1)*B1:B3)
=SUMPRODUCT((Bill, Fred, Steve, Anne, Bill, Fred, Fred, Anne,
Steve=Anne)*(10,10,10,15,15,15,20,20,20))
=SUMPRODUCT((False, False, False, True, False, False, False, True,
False)*(10,10,10,15,15,15,20,20,20))
=SUMPROUDCT((0,0,0,1,0,0,0,1,0)*(10,10,10,15,15,15,20,20,20))
=SUMPRODUCT(0*10+0*10+0*10+1*15+0*15+0*15+0*20+1*20+0*20)
=SUMPRODUCT(0+0+0+15+0+0+0+20+0)
=35

Hope this helps.

--
Cheers
JulieD
Excel MVP

julied_ng at hctsReMoVeThIs dot net dot au


"Victor Chapman" wrote:

> This maybe a strange question, but I have a SUMPRODUCT function that
> works in Excel, however, I don't understand why it does.
>
> Here is what I have:
>
> An array of task times (Duration) B3:B41
>
> A matrix of names of people assigned to the various tasks throughout the
> week (WEEK)D3:H41 (The names appear one or more times)
>
> The array of individual names appears in A43:A61
>
> Now I want to know the total time each individual spends carrying out
> one or more of the tasks. This is done with:
>
> SUMPRODUCT((WEEK=$A43) * Duration)
>
> This function appears beside each name with the row number incremented
> accordingly. IT WORKS!
>
> Here is my problem, I can't find anywhere in the documentation for this
> function (or another example) where a row number in a matrix will look
> up the corresponding row number in an array. So I don't understand why
> it provides the desired result.
>
> I would appreciate more examples of this use of SUMPRODUCT and technical
> explanation of why it works.
>
> TIA
>
>
>
> --
>
> _______________________________
> Regards,
> Vic Chapman
>

[Victor Chapman]

JulieD wrote:
> Hi Victor
>
> Probably the best reference for information on the sumproduct function that
> i know about is at
>
> http://www.xldynamic.com/source/xld.SUMPRODUCT.html
>
> But basically the sumproduct function works by evaluation true statements to
> 1 and false statements to 0 ...
>
> For a quick overview of your sumproduct funtion look at it this way:
> =SUMPRODUCT((WEEK=$A43) * Duration)
> =SUMPRODUCT((D3:H41 =$A43)*B3:B41)
> (for this example i'm make the ranges smaller .... e.g.)
> =SUMPRODUCT((D1:F3 =$G1)*B1:B3)
> (and use the following data)
> ......A........B.........C.........D........E.........F.............G
> 1.............10...................Bill......Fred....Steve.......Anne
> 2.............15...................Anne...Bill.......Fred........Bill
> 3.............20...................Fred....Anne....Steve......Steve
>
> In G2 the SUMPRODUCT formula would work like this
> =SUMPRODUCT((D1:F3 =$G1)*B1:B3)
> =SUMPRODUCT((Bill, Fred, Steve, Anne, Bill, Fred, Fred, Anne,
> Steve=Anne)*(10,10,10,15,15,15,20,20,20))
> =SUMPRODUCT((False, False, False, True, False, False, False, True,
> False)*(10,10,10,15,15,15,20,20,20))
> =SUMPROUDCT((0,0,0,1,0,0,0,1,0)*(10,10,10,15,15,15,20,20,20))
> =SUMPRODUCT(0*10+0*10+0*10+1*15+0*15+0*15+0*20+1*20+0*20)
> =SUMPRODUCT(0+0+0+15+0+0+0+20+0)
> =35
>
> Hope this helps.
>
Thank you for your quick response. I agree, and understand that this is
what the function is doing. What I don't understand is why this works
when it it would appear to be contrary to the information provided in
the Excel Help system. The following is copied from the Help system:

The array arguments must have the same dimensions. If they do not,
SUMPRODUCT returns the #VALUE! error value.

In the example I have provided, Duration is a single column array. WEEK
on the other hand is a multiple column matrix. They have different
dimensions!

To work from your example:

=SUMPRODUCT((D1:F3 =$G1)*B1:B3)

is NOT the same as

=SUMPRODUCT((Bill, Fred, Steve, Anne, Bill, Fred, Fred, Anne,
Steve=Anne)*(10,10,10,15,15,15,20,20,20))

It makes the assumption that for every instance of a row value in WEEK,
the corresponding row value in Duration will be generated. I can't find
anywhere in the documentation that I can make that assumption. I have
also checked http://www.xldynamic.com/source/xld.SUMPRODUCT.html and
cannot find an example similar to the one I have provide.
--

_______________________________
Regards,
Vic Chapman

[Aladin Akyurek]

Victor Chapman wrote:
> JulieD wrote:
>
>> Hi Victor
>>
>> Probably the best reference for information on the sumproduct function
>> that i know about is at
>> http://www.xldynamic.com/source/xld.SUMPRODUCT.html
>>
>> But basically the sumproduct function works by evaluation true
>> statements to 1 and false statements to 0 ...
>>
>> For a quick overview of your sumproduct funtion look at it this way:
>> =SUMPRODUCT((WEEK=$A43) * Duration)
>> =SUMPRODUCT((D3:H41 =$A43)*B3:B41)
>> (for this example i'm make the ranges smaller .... e.g.)
>> =SUMPRODUCT((D1:F3 =$G1)*B1:B3)
>> (and use the following data)
>> ......A........B.........C.........D........E.........F.............G
>> 1.............10...................Bill......Fred....Steve.......Anne
>> 2.............15...................Anne...Bill.......Fred........Bill
>> 3.............20...................Fred....Anne....Steve......Steve
>>
>> In G2 the SUMPRODUCT formula would work like this
>> =SUMPRODUCT((D1:F3 =$G1)*B1:B3)
>> =SUMPRODUCT((Bill, Fred, Steve, Anne, Bill, Fred, Fred, Anne,
>> Steve=Anne)*(10,10,10,15,15,15,20,20,20))
>> =SUMPRODUCT((False, False, False, True, False, False, False, True,
>> False)*(10,10,10,15,15,15,20,20,20))
>> =SUMPROUDCT((0,0,0,1,0,0,0,1,0)*(10,10,10,15,15,15,20,20,20))
>> =SUMPRODUCT(0*10+0*10+0*10+1*15+0*15+0*15+0*20+1*20+0*20)
>> =SUMPRODUCT(0+0+0+15+0+0+0+20+0)
>> =35
>>
>> Hope this helps.
>>
> Thank you for your quick response. I agree, and understand that this is
> what the function is doing. What I don't understand is why this works
> when it it would appear to be contrary to the information provided in
> the Excel Help system. The following is copied from the Help system:
>
> The array arguments must have the same dimensions. If they do not,
> SUMPRODUCT returns the #VALUE! error value.
>
> In the example I have provided, Duration is a single column array. WEEK
> on the other hand is a multiple column matrix. They have different
> dimensions!
>
> To work from your example:
>
> =SUMPRODUCT((D1:F3 =$G1)*B1:B3)
>
> is NOT the same as
>
> =SUMPRODUCT((Bill, Fred, Steve, Anne, Bill, Fred, Fred, Anne,
> Steve=Anne)*(10,10,10,15,15,15,20,20,20))
>
> It makes the assumption that for every instance of a row value in WEEK,
> the corresponding row value in Duration will be generated. I can't find
> anywhere in the documentation that I can make that assumption. I have
> also checked http://www.xldynamic.com/source/xld.SUMPRODUCT.html and
> cannot find an example similar to the one I have provide.

You are multiplying, as it were, a vector with a matrix which are
equally sized in one relevant dimension.