TRUE MATRIX MULTIPLICATION

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##### Question

Hi,

I have a doubt regarding true matrix multiplication.

Thanks!

I have a doubt regarding true matrix multiplication.

matrixA as per the video - 45,49,47,22,21,14,12,13,14

subdata <- captaincy[1:3,c("played","won","lost")]

> matrixA <- as.matrix(subdata)

> print(matrixA)

played won lost

[1] 45 22 12

[2] 49 21 13

[3] 47 14 14

matrixB - my own values <- c(1,0,1,1,0,1,0,1,0)

> matrixB <- matrix(values,nrow=3,ncol=3,byrow=FALSE)

print(matrixB)

[,1] [,2] [,3]

[1,] 1 1 0

[2,] 0 0 1

[3,] 1 1 0

true matric multiplication - matrixA %*% matrixB -

THE RESULTS I AM GETTING ARE -

[,1] [,2] [,3]

1 57 57 22

2 62 62 21

3 61 61 14

THE RESULTS SHOWN IN THE VIDEO - (with matrixB values of his own <-c(1,0,0,0,1,0,0,0,1))

[,1] [,2] [,3]

1 45 22 12

2 49 21 13

3 47 14 14

Could you please explain where am I going wrong ?

Thanks!

R Creating-Matrices-using-Data-Frames 07-08 min 50-60 sec

__Answers:__

There is nothing wrong, the results are different because you have changed matrix B of your own. Each time you change any matrix, the resulting matrix multiplication will be different.

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