In this example DynamicTubeGeometryCaps I had a problem with the tangent some time ago. I solved it there by doing my own calculation. (lines 228 - 244).

I now have a project where this method doesn’t work so I use `.getTangent( t, optionalTarget )`

.

This works in many cases, but for some parameter combinations it gives an incorrect tangent at the end of the curve.

I took a look at the source code:

```
// Returns a unit vector tangent at t
// In case any sub curve does not implement its tangent derivation,
// 2 points a small delta apart will be used to find its gradient
// which seems to give a reasonable approximation
getTangent( t, optionalTarget ) {
const delta = 0.0001;
let t1 = t - delta;
let t2 = t + delta;
// Capping in case of danger
if ( t1 < 0 ) t1 = 0;
if ( t2 > 1 ) t2 = 1;
const pt1 = this.getPoint( t1 );
const pt2 = this.getPoint( t2 );
const tangent = optionalTarget || ( ( pt1.isVector2 ) ? new Vector2() : new Vector3() );
tangent.copy( pt2 ).sub( pt1 ).normalize();
return tangent;
}
```

A fixed value for delta is used. This seems to be the problem. If I set `const delta = 0.01;`

in some of my cases it works. With smaller values the error occurs. But I could not discover a general systematic.

I will now call the method as

```
customGetTangent( t, optionalTarget, delta ) {
// const delta = 0.0001;
...
```

in my code. Then I check if the last tangent deviates strongly and recalculate it with larger delta until it is correct.

*Would it be appropriate to have delta as a parameter in general in the method or is there something against it? Is there a better variant to avoid the error?*