R Under development (unstable) (2023-11-07 r85491 ucrt) -- "Unsuffered Consequences"
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> ##
> ##  g r a d i e n t . R  Test suite
> ##
> 
> 
> gradient <- pracma::gradient
> 
> x <- c(0.0, 0.2, 0.4, 0.6, 0.8, 1.0)
> y <- c(1, 2, 3)
> 
> Z <- matrix(c(
+     1, 1.04, 1.16, 1.36, 1.64,    2,
+     4, 4.04, 4.16, 4.36, 4.64,    5,
+     9, 9.04, 9.16, 9.36, 9.64,   10), nrow = 3, byrow = TRUE)
> 
> X1 <- matrix(c(
+     0.04, 0.08, 0.16, 0.24, 0.32, 0.36,
+     0.04, 0.08, 0.16, 0.24, 0.32, 0.36,
+     0.04, 0.08, 0.16, 0.24, 0.32, 0.36), nrow = 3, byrow = TRUE)
> 
> X2 <- matrix(c(
+     0.2, 0.4, 0.8, 1.2, 1.6, 1.8,
+     0.2, 0.4, 0.8, 1.2, 1.6, 1.8,
+     0.2, 0.4, 0.8, 1.2, 1.6, 1.8), nrow = 3, byrow = TRUE)
> 
> Y <- matrix(c(
+     3, 3, 3, 3, 3, 3,
+     4, 4, 4, 4, 4, 4,
+     5, 5, 5, 5, 5, 5), nrow = 3, byrow = TRUE)
> 
> all.equal(gradient(Z)$X, X1)
[1] TRUE
> all.equal(gradient(Z, x, y)$X, X2)
[1] TRUE
> all.equal(gradient(Z, x, y)$Y, Y)
[1] TRUE
> 
> proc.time()
   user  system elapsed 
   0.14    0.03    0.17