Question

How to perform matrix multiplication with two matrices in R

Answer 1

vec <- c(1, 2, 3, 1, 0, 2, 3, 1, 1)
m1 <- matrix(vec, nrow = 3, ncol = 3)
  
vec <- c(2, 1, 3, 0, 0, 1, 2, 1, 0)
m2 <- matrix(vec, nrow = 3, ncol = 3)
 
mul <- m1 %*% m2

print(m1)
cat('\n')
print(m2)
cat('\n')
print(mul)
 
 
 
 
   
   
# run:
#
#      [,1] [,2] [,3]
# [1,]    1    1    3
# [2,]    2    0    1
# [3,]    3    2    1

#      [,1] [,2] [,3]
# [1,]    2    0    2
# [2,]    1    0    1
# [3,]    3    1    0

#      [,1] [,2] [,3]
# [1,]   12    3    3
# [2,]    7    1    4
# [3,]   11    1    8
#

 

70+ SQL courses for beginners and professionals