Polynomial derivative: Difference between revisions
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Differentiates to
1 - 3x^2- 4x^3</pre>
=={{header|Go}}==
{{trans|Wren}}
<lang go>package main
import (
"fmt"
"strings"
)
func derivative(p []int) []int {
if len(p) == 1 {
return []int{0}
}
d := make([]int, len(p)-1)
copy(d, p[1:])
for i := 0; i < len(d); i++ {
d[i] = p[i+1] * (i + 1)
}
return d
}
var ss = []string{"", "", "\u00b2", "\u00b3", "\u2074", "\u2075", "\u2076", "\u2077", "\u2078", "\u2079"}
// for n <= 20
func superscript(n int) string {
if n < 10 {
return ss[n]
}
if n < 20 {
return ss[1] + ss[n-10]
}
return ss[2] + ss[0]
}
func abs(n int) int {
if n < 0 {
return -n
}
return n
}
func polyPrint(p []int) string {
if len(p) == 1 {
return fmt.Sprintf("%d", p[0])
}
var terms []string
for i := 0; i < len(p); i++ {
if p[i] == 0 {
continue
}
c := fmt.Sprintf("%d", p[i])
if i > 0 && abs(p[i]) == 1 {
c = ""
if p[i] != 1 {
c = "-"
}
}
x := "x"
if i <= 0 {
x = ""
}
terms = append(terms, fmt.Sprintf("%s%s%s", c, x, superscript(i)))
}
for i, j := 0, len(terms)-1; i < j; i, j = i+1, j-1 {
terms[i], terms[j] = terms[j], terms[i]
}
s := strings.Join(terms, "+")
return strings.Replace(s, "+-", "-", -1)
}
func main() {
fmt.Println("The derivatives of the following polynomials are:\n")
polys := [][]int{{5}, {4, -3}, {-1, 6, 5}, {-4, 3, -2, 1}, {1, 1, 0, -1, -1}}
for _, poly := range polys {
deriv := derivative(poly)
fmt.Printf("%v -> %v\n", poly, deriv)
}
fmt.Println("\nOr in normal mathematical notation:\n")
for _, poly := range polys {
deriv := derivative(poly)
fmt.Println("Polynomial : ", polyPrint(poly))
fmt.Println("Derivative : ", polyPrint(deriv), "\n")
}
}</lang>
{{out}}
<pre>
The derivatives of the following polynomials are:
[5] -> [0]
[4 -3] -> [-3]
[-1 6 5] -> [6 10]
[-4 3 -2 1] -> [3 -4 3]
[1 1 0 -1 -1] -> [1 0 -3 -4]
Or in normal mathematical notation:
Polynomial : 5
Derivative : 0
Polynomial : -3x+4
Derivative : -3
Polynomial : 5x²+6x-1
Derivative : 10x+6
Polynomial : x³-2x²+3x-4
Derivative : 3x²-4x+3
Polynomial : -x⁴-x³+x+1
Derivative : -4x³-3x²+1
</pre>
=={{header|Haskell}}==
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