This is a simple example of a 2 dimensional lookup table with linear interpolation in Go.

lookup2d.go

package main

import (
	"fmt"
)

func main() {

	var yi1, yi2, xi1, xi2 int     // Lookup table indexes around point
	var x, y float64               // x,y axis values at indexes
	var y1, y2, x1, x2 float64     // Axis values of indexes
	var q11, q12, q21, q22 float64 // xy, lookup values at indexes

	xAxis := []float64{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
	yAxis := []float64{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

	lookup := [][]float64{
		{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10},
		{1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10},
		{2, 2, 2, 3, 4, 5, 6, 7, 8, 9, 10},
		{3, 3, 3, 3, 4, 5, 6, 7, 8, 9, 10},
		{4, 4, 4, 4, 4, 5, 6, 7, 8, 9, 10},
		{5, 5, 5, 5, 5, 5, 6, 7, 8, 9, 10},
		{6, 6, 6, 6, 6, 6, 6, 7, 8, 9, 10},
		{7, 7, 7, 7, 7, 7, 7, 7, 8, 9, 10},
		{8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 10},
		{9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10},
		{10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10},
	}

	// Input values
	x = 3.45
	y = 5.78

	for i, v := range xAxis {
		if v >= x {
			x1, x2 = xAxis[i-1], xAxis[i]
			xi1, xi2 = i-1, i
			break
		}
	}

	for i, v := range yAxis {
		if v >= y {
			y1, y2 = yAxis[i-1], xAxis[i]
			yi1, yi2 = i-1, i
			break
		}
	}

	q11 = lookup[xi1][yi1]
	q12 = lookup[xi1][yi2]
	q21 = lookup[xi2][yi1]
	q22 = lookup[xi2][yi2]

	d := (x2 - x1) * (y2 - y1)
	t1 := (((x2 - x) * (y2 - y)) / d) * q11
	t2 := (((x - x1) * (y2 - y)) / d) * q21
	t3 := (((x2 - x) * (y - y1)) / d) * q12
	t4 := (((x - x1) * (y - y1)) / d) * q22

	val := t1 + t2 + t3 + t4

	fmt.Println("Between x:", x1, x2)
	fmt.Println("Between y:", y1, y2)
	fmt.Println("Calculated:", val)
}