1 | initial version |

the first code in the question does not work for me with Ubuntu 18.04 notebook SageMath 9.1, but I noticed that if we ask for the graph of a function outside its domain of definition it causes a verbose and moreover the graph refuses to extend at the requested values

```
r=1
C_d(x)= -sqrt(r^2-x^2)
gf+=plot(C_d,(x,-2,2),color='black') #produce verbose and do not span
#gf+=plot(C_d,(x,-1,1),color='black') # no verbose
show(gf,aspect_ratio=1)
```

2 | No.2 Revision |

the first code in the question does not work for me with Ubuntu 18.04 notebook SageMath 9.1, but I noticed that if we ask for the graph of a function outside its domain of definition it causes a verbose and moreover the graph refuses to extend at the requested values

```
r=1
C_d(x)= -sqrt(r^2-x^2)
```~~gf+=plot(C_d,(x,-2,2),color='black') ~~gf=plot(C_d,(x,-2,2),color='black') #produce verbose and do not span
~~#gf+=plot(C_d,(x,-1,1),color='black') ~~#gf=plot(C_d,(x,-1,1),color='black') # no verbose
show(gf,aspect_ratio=1)

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