test.cpp:
#include <iostream>

const int N = 1001;
double y[N] = {0.0};
double dx = 1.0/(N-1);

void solve() {
    for (int i = 1; i < N-1; i++) {
        y[i] = -0.5*(-dx*dx - (y[i-1] + y[i+1]));
    }
}

int main() {
    y[N-1] = 1.0;
    for (int i = 0; i < N*100; i++)
        solve();

    // for (int i = 0; i < N; i++)
    //  std::cout << i*dx << " " << y[i] << std::endl;
    return 0;
}



test.go:
package main

import (
    "fmt"
)

var _ =  fmt.Println

const N = 1001
var y [N]float64
var dx = 1.0/(N-1)

func solve() {
    for i := 1; i < N-1; i++ {
        y[i] = -0.5*(-dx*dx - (y[i-1] + y[i+1]));
    }
}

func main() {
    y[N-1] = 1.0
    for i := 0; i < 100*N; i++ {
        solve()
    }

    // for i,v := range y {
    //  fmt.Println(float64(i)*dx,v)
    // }

}