Distance Calculation Methods

Select two points on the map to compare different distance calculation methods

Distance Comparison

1. Haversine Formula (Current Method) ±0.5% Error

Calculates the straight-line distance on a sphere. Fast and simple.

-- km 
function haversine(lat1, lon1, lat2, lon2) {
    const R = 6371; // Earth radius in km
    const dLat = (lat2 - lat1) * Math.PI / 180;
    const dLon = (lon2 - lon1) * Math.PI / 180;
    const a = Math.sin(dLat/2) * Math.sin(dLat/2) +
              Math.cos(lat1 * Math.PI / 180) *
              Math.cos(lat2 * Math.PI / 180) *
              Math.sin(dLon/2) * Math.sin(dLon/2);
    const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
    return R * c;
}

Pros: Fast, simple, good for short distances
Cons: Assumes Earth is a perfect sphere (it's actually an ellipsoid)

2. Vincenty Formula ±0.01% Error

Calculates distance on an ellipsoid (Earth's actual shape). More accurate.

-- km 
function vincenty(lat1, lon1, lat2, lon2) {
    const a = 6378137, b = 6356752.314245, f = 1/298.257223563;
    const L = (lon2 - lon1) * Math.PI / 180;
    const U1 = Math.atan((1 - f) * Math.tan(lat1 * Math.PI / 180));
    const U2 = Math.atan((1 - f) * Math.tan(lat2 * Math.PI / 180));
    // ... iterative calculation (complex)
    return distance / 1000; // Convert to km
}

Pros: Very accurate for geodetic calculations
Cons: More complex, slower computation

3. Road/Driving Distance Most Practical

Calculates the actual route distance following roads. Best for towing services!

Calculating... 
// Using OSRM (Open Source Routing Machine) API
const url = `https://router.project-osrm.org/route/v1/driving/
             ${lon1},${lat1};${lon2},${lat2}?overview=false`;
fetch(url)
    .then(res => res.json())
    .then(data => {
        const distance = data.routes[0].distance / 1000;
        console.log('Road distance:', distance, 'km');
    });

Pros: Real-world accurate, includes road network
Cons: Requires API call, slower, needs internet

Difference Analysis

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Recommendation for Towing Service:

Use Road Distance (Method 3) for the most accurate pricing because:

Fallback: Use Haversine as a quick estimate or backup when API is unavailable.