MATRIX CALCULATIONS IN R


R version 3.1.2 (2014-10-31) -- "Pumpkin Helmet"
Copyright (C) 2014 The R Foundation for Statistical Computing
Platform: x86_64-w64-mingw32/x64 (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
Type 'license()' or 'licence()' for distribution details.

> lotsize<-read.table(stdin(), header=F)
0: 80  399
1: 30  121
2: 50  221
3: 90  376
4: 70  361
6: 60  224
7: 120  546
8: 80  352
9: 100  353
10: 50  157
11: 40  160
12: 70  252
13: 90  389
14: 20  113
15: 110  435
16: 100  420
17: 30  212
18: 50  268
19: 90  377
20: 110  421
21: 30  273
22: 90  468
23: 40  244
24: 80  342
25: 70  323
26: 
> summary(lotsize)
       V1            V2       
 Min.   : 20   Min.   :113.0  
 1st Qu.: 50   1st Qu.:224.0  
 Median : 70   Median :342.0  
 Mean   : 70   Mean   :312.3  
 3rd Qu.: 90   3rd Qu.:389.0  
 Max.   :120   Max.   :546.0  
>
> X<-cbind(rep(1,25),lotsize$V1)
> Y<-lotsize$V2
>
> xpx <- t(X)%*%X
> xpx
     [,1]   [,2]
[1,]   25   1750
[2,] 1750 142300
>
> xpy <- t(X)%*%Y
> xpy
       [,1]
[1,]   7807
[2,] 617180
> b<-solve(xpx)%*%xpy
> b
          [,1]
[1,] 62.365859
[2,]  3.570202