aaa.R

require(multipol)



# Some tests, which I just made up.  It would be good to verify
# Euler's four-square identity, but this takes too long.

x <- # x is the first three columns of a 21x21 magic square
structure(c(209L, 187L, 165L, 143L, 121L, 99L, 77L, 55L, 33L,
11L, 430L, 408L, 386L, 364L, 342L, 320L, 298L, 276L, 254L, 232L,
231L, 186L, 164L, 142L, 120L, 98L, 76L, 54L, 32L, 10L, 429L,
407L, 385L, 363L, 341L, 319L, 297L, 275L, 253L, 252L, 230L, 208L,
163L, 141L, 119L, 97L, 75L, 53L, 31L, 9L, 428L, 406L, 384L, 362L,
340L, 318L, 296L, 274L, 273L, 251L, 229L, 207L, 185L), .Dim = c(21L,
3L))

a <- as.multipol(array(1:12,c(2,3,2)))  #just a random multipol
f1 <- as.function(a)
f2 <- as.function(a*a)

x1 <- floor(x/7)  

stopifnot(all(f1(x1)^2 == f2(x1)))

# Now some elementary factorizations (also given, but not verified, on
# constant.Rd):

# Factorize x^2 - y^2:
lhs <- ones(2) * linear(c(1,-1))    # (x+y)(x-y)
rhs <- single(2,1,2)-single(2,2,2)  # x^2-y^2
stopifnot(is.zero(rhs-lhs))

# Now factorize x^2 + y^2:
lhs <- linear(c(1,1i)) * linear(c(1,-1i))  # (x+iy)*(x-iy)
rhs <- ones(2,2)                           # x^2 + y^2
stopifnot(is.zero(rhs-lhs))

# Now factorize x^3 + y^3:
lhs <- ones(2) * (linear(c(1,1),2)-uni(2))   # (x+y)(x^2-xy+y^2)
rhs <- single(2,1,3) + single(2,2,3)
stopifnot(is.zero(rhs-lhs))

# Now x^5 + y^5:
lhs <- ones(2) * homog(2,4,c(1,-1,1,-1,1))  # (x+y) * ...
rhs <- single(2,1,5) + single(2,2,5)        # x^5+y^5 
stopifnot(is.zero(rhs-lhs))

# xyz = x*y*z:
lhs <- uni(3)
rhs <- single(3,1) * single(3,2) * single(3,3)
stopifnot(is.zero(rhs-lhs))

# x+y+z == x+y+z:
lhs <- single(3,1) + single(3,2) + single(3,3)
rhs <- ones(3)
stopifnot(is.zero(rhs-lhs))



# Now some tests of deriv:

a <- as.multipol(matrix(1:12,3,4))
da1 <- deriv(a,1)
da2 <- deriv(a,2)

stopifnot(all(da1 == matrix(c(2,6,5,12,8,18,11,24    ),nrow=2)))
stopifnot(all(da2 == matrix(c(4,5,6,14,16,18,30,33,36),nrow=3)))

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