script.js

const predict=(e)=>{
    e.preventDefault();
    const output=document.getElementById('output');

    const input_a=document.getElementById('a');
    const input_b=document.getElementById('b');
    const input_c=document.getElementById('c');
    
    const a=parseFloat(input_a.value);
    const b=parseFloat(input_b.value);
    const c=parseFloat(input_c.value);
    if(a>36 || a<0 || b<0 || b>36 || c>36 || c<0 || isNaN(a) || isNaN(b) || isNaN(c)){
        output.textContent=("please enter value between 0.00 to 36.00");
        output.style.color="red";
        return; 
    }
    console.log(a,b,c);
    const spi=query(a,b,c);
    
    output.textContent="Predicited Approximate SPI : "+spi.toFixed(2);
    output.style.color="green";
}
const query=(a,b,c)=>{
    const mean_bias = 1.99862
    const coef=[
        0.04031820967793465  , 
        0.09917458146810532  , 
        0.0819840207695961  , 
    ];
    const spi=a*coef[0]+b*coef[1]+c*coef[2]+mean_bias;
    return spi;
}