poly: improvements, tests and examples

examples/poly_eval/README.md

@@ -0,0 +1,17 @@
+# Example - poly_eval 📘
+
+This example demonstrates the usage of the V Scientific Library for evaluating polynomial at given
+value of x.
+
+## Instructions
+
+1. Ensure you have the V compiler installed. You can download it from [here](https://vlang.io).
+2. Ensure you have the VSL installed. You can do it following the [installation guide](https://github.com/vlang/vsl?tab=readme-ov-file#-installation)!
+3. Navigate to this directory.
+4. Run the example using the following command:
+
+```sh
+v run main.v
+```
+
+Enjoy exploring the capabilities of the V Scientific Library! 😊

examples/poly_eval/main.v

@@ -0,0 +1,11 @@
+module main
+
+import vsl.poly
+
+fn main() {
+	// represent the polynomial 2 * x^2 + 5 * x + 4
+	// with x = 4, result is 2 * 4^2 + 5 * 4 + 4 = 56
+	coef := [4.0, 5, 2]
+	result := poly.eval(coef, 4)
+	println('Evalutated value: ${result}')
+}

examples/poly_operations/README.md

@@ -0,0 +1,17 @@
+# Example - poly_eval 📘
+
+This example demonstrates the usage of the V Scientific Library for additioning, substracting and
+multiplying polynomials.
+
+## Instructions
+
+1. Ensure you have the V compiler installed. You can download it from [here](https://vlang.io).
+2. Ensure you have the VSL installed. You can do it following the [installation guide](https://github.com/vlang/vsl?tab=readme-ov-file#-installation)!
+3. Navigate to this directory.
+4. Run the example using the following command:
+
+```sh
+v run main.v
+```
+
+Enjoy exploring the capabilities of the V Scientific Library! 😊

examples/poly_operations/main.v

@@ -0,0 +1,23 @@
+module main
+
+import vsl.poly
+
+fn main() {
+	// Addition
+	// Degree is not modified unless highest coefficients cancel each other out
+	poly_1 := [1.0, 12, 3]
+	poly_2 := [3.0, 2, 7]
+	result_add := poly.add(poly_1, poly_2)
+	println('Addition result: ${result_add}')
+
+	// Substraction
+	// Degree is not modified unless highest coefficients cancel each other out
+	result_sub := poly.substract(poly_1, poly_2)
+	println('Substraction result: ${result_sub}')
+
+	// Multiplication
+	// with given degree n and m for poly_1 and poly_2
+	// resulting polynomial will be of degree n + m
+	result_mult := poly.multiply(poly_1, poly_2)
+	println('Multplication result: ${result_mult}')
+}

poly/poly.v

@@ -10,9 +10,11 @@ pub fn eval(c []f64, x f64) f64 {
 		panic('coeficients can not be empty')
 	}
 	len := c.len
-	mut ans := c[len - 1]
-	for e in c[..len - 1] {
-		ans = e + x * ans
+	mut ans := 0.0
+	mut i := len - 1
+	for i >= 0 {
+		ans = c[i] + x * ans
+		i--
 	}
 	return ans
 }
@@ -131,13 +133,13 @@ fn sorted_3_(x_ f64, y_ f64, z_ f64) (f64, f64, f64) {
 	mut y := y_
 	mut z := z_
 	if x > y {
-		y, x = swap_(x, y)
+		x, y = swap_(x, y)
 	}
-	if y > z {
-		z, y = swap_(y, z)
+	if x > z {
+		x, z = swap_(x, z)
 	}
-	if x > y {
-		y, x = swap_(x, y)
+	if y > z {
+		y, z = swap_(y, z)
 	}
 	return x, y, z
 }

poly/poly_test.v

@@ -2,11 +2,11 @@ module poly
 
 fn test_eval() {
 	// ans = 2
-	// ans = 4.0 + 4 * 2 = 12
-	// ans = 5 + 4 * 12 = 53
+	// ans = 5 + 4 * 2 = 13
+	// ans = 4 + 4 * 13 = 56
 	x := 4
 	cof := [4.0, 5, 2]
-	assert eval(cof, 4) == 53
+	assert eval(cof, 4) == 56
 }
 
 fn test_swap() {
@@ -16,13 +16,13 @@ fn test_swap() {
 	assert a == 202.0 && b == 101.0
 }
 
-// fn test_sorted_3_(){
-// 	a := 5.0
-// 	b := 7.0
-// 	c := -8.0
-// 	x, y, z := sorted_3_(a, b, c)
-// 	assert y == 7.0
-// }
+fn test_sorted_3_() {
+	a := 5.0
+	b := 7.0
+	c := -8.0
+	x, y, z := sorted_3_(a, b, c)
+	assert x == -8.0 && y == 5.0 && z == 7.0
+}
 
 fn test_add() {
 	a := [6.0, 777, -3]
@@ -36,9 +36,9 @@ fn test_substract() {
 	assert substract(a, b) == [5.0, 1532, 1]
 }
 
-// fn test_multiply(){
-// 	a := [9.0, -1, 5]
-// 	b := [0.0, -1, 7]
+fn test_multiply() {
+	a := [9.0, -1, 5]
+	b := [0.0, -1, 7]
 
-// 	assert multiply(a, b) == [0.0, -9, 73, -12, 35, 0]
-// }
+	assert multiply(a, b) == [0.0, -9, 64, -12, 35, 0]
+}