在 R 编程中计算表达式的导数 - deriv() 和 D()函数

在 R 编程中，可以使用deriv()和D() 函数计算函数的导数。它用于计算简单表达式的导数。

Syntax:
deriv(expr, name)
D(expr, name)

Parameters:
expr: represents an expression or a formula with no LHS
name: represents character vector to which derivatives will be computed

示例 1：

# Expression or formula
f = expression(x^2 + 5*x + 1)
  
# Derivative
cat("Using deriv() function:\n")
print(deriv(f, "x"))
  
cat("\nUsing D() function:\n")
print(D(f, 'x'))

输出：

Using deriv() function:
expression({
    .value <- x^2 + 5 * x + 1
    .grad <- array(0, c(length(.value), 1L), list(NULL, c("x")))
    .grad[, "x"] <- 2 * x + 5
    attr(.value, "gradient") <- .grad
    .value
})

Using D() function:
2 * x + 5

示例 2：

# Little harder derivative
  
# Using deriv() Function
cat("Using deriv() function:\n")
print(deriv(quote(sinpi(x^2)), "x"))
  
# Using D() Function
cat("\nUsing D() function:\n")
print(D(quote(sinpi(x^2)), "x"))

输出：

Using deriv() function:
expression({
    .expr1