Matrix Algebra

[#1]

Hi all,

Does anyone know if qlikview has the ability to multiply out matrices (something equivalent to =MMULT in excel)?

We are trying to multiply a fixed (50x50) matrix with a slider-controlled 50x1 price vector.

i.e.

Matrix                                 

      A     B      C

A    1      3      2

B    2      1      2 

C    5      1      0

Price vector (i.e. Slider sets A to 2)

A  2

B  0

C 0

Ouput:

A =1*2 + 3*0 + 2*0 =  2

B =2*2 + 1*0 + 2*0 = 4

C= 5*2 + 1*0 + 0*0 = 10

Have thought about writing the whole formula out but it does not seem possbile to specify particular cells (just columns).

Would appreciate any advice/insight.

Thanks!

[#2]

Hi James,

you could get specific 'fields' with a sorted table and peek to defined rows.

What is the formula besides the syntax of Excel or QlikView?

Ciao

Klaus

[Anonymous]

I am afraid not.

I think the best way is to transform your scalar operation into a simple linear operation.

In QV, you have a Crosstable interpretation, transform your matrix into the following:

AA, AB, AC, BA, BB, BC, CA, CB, CC
1, 3, 2, 2, 1, 2, 5, 1, 0

A,B,C

2, 0, 0

Resultante:

AA*A, AB*B, AC*C BA*A, BB*B, BC*C, CA*A, CB*B, CC*C (edited: corrected the appropriate vector index)

You will have to code...

Hope this helps

(and let me know if you found a faster way )

Cheers,

Antoine

[#4]

Does the below help you?

Data1:
LOAD * INLINE [
    A, B, C
    1, 3, 2
    2, 1, 2
    5, 1, 0
];

Data2:
Load * INLINE [
  pA, pB, pC
  2, 0, 0
];

let nRows1 = NoOfRows('Data1')-1;
let nRows2 = NoOfRows('Data2')-1;

for i = 0 to nRows1
    let vA = peek('A',$(i),'Data1');
    let vB = peek('B',$(i),'Data1');
    let vC = peek('C',$(i),'Data1');
   
    for j = 0 to nRows2
        let vpA = peek('pA',$(j),'Data2');
        let vpB = peek('pB',$(j),'Data2');
        let vpC = peek('pB',$(j),'Data2');

        Data3:
        load
           ($(vA) * $(vpA)) + ($(vB) * $(vpB)) + ($(vC) * $(vpC)) as xA
        AutoGenerate(1);

    next j;
   
next i;

[#5]

I had a similar requirement as with original poster.  The post by Sajeevan Govindan helped.

[imsushantjain]

I am in similar situation, any update on Matrix Multiplication would be very helpful!

[imsushantjain]

Any pointer for matrix as large as 5000x5000 and can increase dynamically, would you recommend this solution?

i believe i have to even loop statement likes let vA = peek('A',$(i),'Data1'); but that will increase the complexity as well.