1 | initial version |

This has to do with the implementation of `piecewise`

, I think.

I can get a numerical integral to work by doing the following:

```
phi(x)=(heaviside(x+1)-heaviside(x-1))*(1-abs(x))*(1-abs(x))*(1+2*abs(x))
numerical_integral(phi(x/h-1),0,pi)
```

Another option would be to stop the integral at the point at which the function is zero.

```
phi2(x)=(1-abs(x))*(1-abs(x))*(1+2*abs(x))
integral(phi2(x/h-1),x,0,2*pi/n)
```

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