unit1 added

Author: eliastor

README.md

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+# Golang in Systems Engineering 101
+
+## Requirements
+1. [VSCode](https://code.visualstudio.com/download)
+2. [installed go](https://go.dev/dl)
+3. [Go plugin in VSCode](vscode:extension/golang.Go)
+
+## Structure
+
+This course consists of topics.
+Each topic has trainin materials, hints, quizes and excersices.
+
+Each quiz should be solved, and answers should be sent as replies in Issues for respective Unit or directly to me.
+
+Each exercies should be solved, and answers should be placed to respective folder sent in Pull Request to this repository. See Unit 1 Exercise 1 for more info.
+
+If case of any question don't hesitate to use Issues or contact me directly.
+
+Sync the main branch form time to time, new units and FAQs are being added.
+
+## Unit 1: A tour of Go
+Here are basics of Go we should understand.
+
+ETC: 7-8 hours
+
+More on [unit folder](unit1)

unit1/README.md

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+# Unit 1: A tour of Go
+Please finish all material on https://go.dev/tour/ or https://go.dev/tour/list except "Generics" and "Concurrency"
+
+Note: if you stuck with module try to read https://go.dev/blog/using-go-modules.
+
+### Quiz
+
+#### Q1. How will you add the number 3 to the right side?
+
+`numbers := []int{1, 1, 2}`
+
+1. `numbers.append(3)`
+2. `numbers.insert(3, 3)`
+3. `append(numbers, 3)`
+4. `numbers = append(numbers, 3)`
+
+#### Q2. From where is the variable fooVar accessible if it is declared outside of any functions in a file in package fooPackage located inside module fooModule
+
+1. anywhere inside `fooPackage`, not the rest of `fooModule`
+2. by any application that imports `fooModule`
+3. from anywhere in `fooModule`
+4. by other packages in `fooModule` as long as they import `fooPackage`
+
+### Q3. What should the idiomatic name be for an interface with a single method and the signature Serve() error
+
+1. Servable
+2. Server
+3. ServeInterface
+4. IServe
+
+### Q4. Which is **not** valid loop construct?
+
+1. `for i,r:=0,rand.Int(); i < r%10; i++ { ... }`
+2. `for { ... }`
+3. `{ ... } for false` 
+4. `for _,c := range "foobar" { ... }`
+
+## Excercises
+`E0` is for illustration how to work and submit Excercises.
+Let's make 
+
+### E0. Exercise: Loops and Functions
+More: https://go.dev/tour/flowcontrol/8
+let's create implementation in `unit1/exercises/e0/main.go`, wherer `unit1` is number of current unit, `e0` is number of current exercise.
+
+If task has multiple steps to do, we assume that the last steps is final. Input values must be the same as in Exercie definition if other is not mentioned. 
+
+At first we've been asked to implement Sqrt function with partial implementation of Newton method and send output of computation steps on each iteration of method:
+
+```go
+package main
+
+import (
+	"fmt"
+)
+
+func Sqrt(x float64) float64 {
+	z := 1.0
+	for i:=0; i<10; i++ {
+		delta := (z*z - x) / (2*z)
+		z -= delta
+		fmt.Println(z)
+	}
+	return z
+}
+
+func main() {
+	fmt.Println(Sqrt(2))
+}
+```
+
+Next we've asked to change loop condition to stop once the value has stopped changing (or only changes by a very small amount). We can achieve that by adding `epsilon` constant that will be compared with `delta`. 
+**Note that their absolute values should be compared**. One approach is to use `Abs()` function form `math` package, or we can notice that `x` argument must be positive and kae our own condition based on partial comparison of positive-only numbers:
+
+```go
+package main
+
+import (
+	"fmt"
+)
+
+func Sqrt(x float64) float64 {
+	epsilon := 0.0000000000001
+	z := 1.0
+	for {
+		delta := (z*z - x) / (2 * z)
+        // or: if math.Abs(delta) < epsilon {
+		if delta < epsilon && delta > -epsilon {
+			break
+		}
+		z -= delta
+		fmt.Println(z)
+	}
+	return z
+}
+
+func main() {
+	fmt.Println(Sqrt(2))
+}
+```
+
+If you haven't managed to solve all steps publish code for the step you succeeded and make a comment in code.
+If you exercise requires to make multiple files or even pacakges, don't hesitate to create them in `unit1/exercises/eX/` folder
+
+As soon as you implemented the code and place it into `unit1/exercises/e0/main.go`, make PR to this repo.
+
+### E1. Fibonacci closure
+More: https://go.dev/tour/moretypes/26
+
+Share your implementation `unit1/exercises/e1/main.go` in github PR.
+
+### E2. Stringers
+More: https://go.dev/tour/methods/18
+
+Share your implementation  `unit1/exercises/e2/main.go` in github PR.
+
+### E3. Errors
+More: https://go.dev/tour/methods/20
+
+Share your implementation  `unit1/exercises/e3/main.go` in github PR.
+
+### E4. rot13Reader
+More: https://go.dev/tour/methods/23
+
+Share your implementation  `unit1/exercises/e4/main.go` in github PR.
+
+### E5. Images
+More: https://go.dev/tour/methods/25
+
+Share your implementation  `unit1/exercises/e5/main.go` in github PR.

unit1/exercises/e0/.gitkeep

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+package main
+
+import (
+	"fmt"
+)
+
+func Sqrt(x float64) float64 {
+	epsilon := 0.0000000000001
+	z := x / 2
+	for {
+		delta := (z*z - x) / (2 * z)
+		if delta < epsilon && delta > -epsilon {
+			break
+		}
+		z -= delta
+		fmt.Println(z)
+	}
+	return z
+}
+
+func main() {
+	fmt.Println(Sqrt(2))
+}