Why is this printing NaN?

Question

EDIT:

onst grades = [
{
value: 'null',
label: 'None',
},
{
value: 10,
label: 'O',
},
{
value: 9,
label: 'A+',
},
{
value: 8,
label: 'A',
}
];

export default function Calculator() {
const n = 5;
var [matrix, setMatrix] = React.useState(Array.from({length: n},()=> Array.from({length: 3}, () => null)));
const handleChange = (row, column, event) => {
let copy = [...matrix];
copy[row][column] = event.target.value;
setMatrix(copy);

console.log(matrix);
};

const gpaCalculate = () => {
let copy = [...matrix];
var credit, grade, sumpoints, sumCredits;
copy.map(rows => {
if(rows[1]=="") {
credit = 0;
}
else {
credit = parseInt(rows[1]);
}
grade = parseInt(rows[2]);
console.log(credit, grade);
console.log(typeof(credit), typeof(grade));
sumpoints += parseInt(credit * grade);
sumCredits += parseInt(credit);
console.log(sumpoints, sumCredits);
})
console.log(sumpoints, sumCredits);
var gpa = (sumpoints/sumCredits);
console.log("GPA", gpa);
};

return (
<Box sx={{ px: 20, m: 3 }}>
<Grid container justifyContent="center" alignItems="center">
<Grid item xs={12} sm={8}>
<Typography variant="h1">GPA Calculator</Typography>
<TableContainer component={ Paper } elevation={ 3 } sx={{ width: 'max-content' }}>
<Table aria-label="GPA calculating table">
<TableHead>
<TableRow>
<TableCell>Sr.</TableCell>
<TableCell>Course</TableCell>
<TableCell

Answer 1

This code cannot output anything to the console because there is no call to graCalculate() and no matrix value. 🤔

Answer 2

As Vasilly said, the function is not being called, and missing info in what <matrix> is. Please rather save a copy of the code in SoloLearn and share its link. With more info revealed, hopefully we can work something out.

https://www.sololearn.com/post/75089/?ref=app