test_that("sum", {

    skip_if_no_sympy()
  
    a <- c("x", "x^2")
    b <- as_sym(a)
    expect_equal(as.character(sum(b)), "x^2 + x")
    
    p <- as_sym(paste0("p", 1:3))
    y <- as_sym(paste0("y", 1:3))
    w <- as_sym("w")
    sum(w)


    a <- as_sym("a")
    expect_equal(as.character(sum(a)), "a")

    l <- sum(y*log(p))
    expect_equal(as.character(l), "y1*log(p1) + y2*log(p2) + y3*log(p3)")
    
    A <- matrix(c("x", 0, 0, "2*x", "3*x**2", "-1"), 2, 3)
    B <- as_sym(A)
    expect_equal(as.character(sum(B)), "3*x^2 + 3*x - 1")


})

test_that("cbind/rbind", {
  skip_if_no_sympy()
  
  x <- symbol("x")
  
  expect_equal(as.character(cbind(x, x, x)), "Matrix([[x, x, x]])")
  expect_equal(as_character_matrix(cbind(x, x, x)), 
               structure(c("x", "x", "x"), .Dim = c(1L, 3L)))
  
  expect_equal(as.character(rbind(x, x, x)), "Matrix([[x], [x], [x]])")
  expect_equal(as_character_matrix(rbind(x, x, x)), 
               structure(c("x", "x", "x"), .Dim = c(3L, 1L)))
  
  
  
  a <- c("x", "x^2")
  b <- as_sym(a)
  
  expect_equal(unname(cbind(a, a, a)), 
               as_character_matrix(cbind(b, b, b)))
  expect_equal(as.character(cbind(b, 2*b, b-1)), 
               "Matrix([[x, 2*x, x - 1], [x^2, 2*x^2, x^2 - 1]])")
  expect_equal(as_character_matrix(cbind(b, 2*b, b-1)), 
               structure(c("x", "x^2", "2*x", "2*x^2", "x - 1", "x^2 - 1"), .Dim = 2:3))
  
  expect_equal(unname(rbind(a, a, a)), 
               as_character_matrix(rbind(t(b), t(b), t(b))))
  expect_equal(as.character(rbind(b, 2*b, b-1)), 
               "Matrix([[x, x^2], [2*x, 2*x^2], [x - 1, x^2 - 1]])")
  expect_equal(as.character(rbind(t(b), t(2*b), t(b-1))), 
               "Matrix([[x, x^2], [2*x, 2*x^2], [x - 1, x^2 - 1]])")
  expect_equal(as_character_matrix(rbind(t(b), t(2*b), t(b-1))), 
               structure(c("x", "2*x", "x - 1", "x^2", "2*x^2", "x^2 - 1"), .Dim = 3:2))
})


test_that("rev", {
  skip_if_no_sympy()
  
  a <- c("x", "x^2")
  x <- as_sym(a)
  
  y1 <- rev(x)
  y2 <- as_sym(rev(a))
  expect_equal(as.character(y1), as.character(y2))
})


test_that("c", {
  skip_if_no_sympy()
  
  v <- vector_sym(3)
  expect_equal(as.character(c(v, v)), "Matrix([[v1], [v2], [v3], [v1], [v2], [v3]])")
  
  A <- matrix_sym(4, 3)
  expect_equal(as.character(c(A)), "Matrix([[v11], [v21], [v31], [v41], [v12], [v22], [v32], [v42], [v13], [v23], [v33], [v43]])")
  
  expect_equal(as.character(c(A, v)), "Matrix([[v11], [v21], [v31], [v41], [v12], [v22], [v32], [v42], [v13], [v23], [v33], [v43], [v1], [v2], [v3]])")
})



test_that("rep", {
  skip_if_no_sympy()
  
  v <- as_sym(c("x", "x^2"))
  expect_equal(as.character(rep(v, 2)), "Matrix([[x], [x^2], [x], [x^2]])")
  
  v <- vector_sym(3)
  expect_equal(as.character(rep(v, 2)), "Matrix([[v1], [v2], [v3], [v1], [v2], [v3]])")
})



test_that("matrify", {
  skip_if_no_sympy()
  
  x <- symbol("x")
  y <- symbol("y")
  f <- 3*x^2 + x*y^2
  expect_equal(as.character(matrify(f)), "Matrix([[3*x^2 + x*y^2]])")
  
  h <- der2(f, list(x, y))
  expect_equal(as.character(matrify(h)), "Matrix([[6, 2*y], [2*y, 2*x]])")
})