Hi there. So as of late, ImageJ’s Curve Fitter tool includes the error function as:

y = a+b*erf((x-c)/d)

The fit runs fine when called as

```
Fit.doFit("Error Function", values, counts);
```

but since I’m doing a reconvolution of a biexponential curve by a Gaussian, I need to fit to an equation with two terms that are both multiplied by an error function. The macro however does not recognize the “erf” substring as an operator in a function when it’s entered in an equation.

I tried simply executing a macro code that called the same equation as the default “Error Function” option:

```
Fit.doFit("y=a+b*erf((x-c)/d)", values, counts);
```

and, again, it doesn’t recognize the “erf” operator.

Any suggestion as to why this keeps happening and/or how to avoid it? I tried using numerical approximations to the error function, but those led to an extremely cumbersome equation that was prone to give very… inaccurate fits.

Thanks in advance.