# double division by zero inconsistency

Division by zero with doubles will throw an exception if both arguments are boxed, but not otherwise:

```
Clojure 1.9.0-beta1
user=> (/ 5.0 0.0)

### Inf

user=> (/ (identity 5.0) 0.0)

### Inf

user=> (/ 5.0 (identity 0.0))

### Inf

user=> (/ (identity 5.0) (identity 0.0))
ArithmeticException Divide by zero clojure.lang.Numbers.divide (Numbers.java:163)
```

by

So, I guess some division by zero is somewhat undefined.
If one removes

```

``````if(yops.isZero((Number)y))
throw new ArithmeticException("Divide by zero");
``````

```

then

` (/ (identity 5.0) (identity 0.0))`

returns infinity as the unboxed versions.

Although doing so, also causes a change to

`(/ 5 0)`

which then becomes `1/0`, whereas it previously threw Divide by zero.

From Numbers.java we see that unboxed math does not protect against division by zero:

```
static public double divide(double x, double y){

``````return x / y;
``````

}
```

whereas boxed versions do:

```
static public Number divide(Object x, Object y){

``````if (isNaN(x)){
return (Number)x;
} else if(isNaN(y)){
return (Number)y;
}
Ops yops = ops(y);
if(yops.isZero((Number)y))
throw new ArithmeticException("Divide by zero");
return ops(x).combine(yops).divide((Number)x, (Number)y);
``````

}
```

This inconsistency is also reproducible with clojure 1.8:

```
Clojure 1.8.0
Java HotSpot(TM) 64-Bit Server VM 1.8.0_144-b01

``````Docs: (doc function-name-here)
(find-doc "part-of-name-here")
``````

Source: (source function-name-here)

``````Exit: Control+D or (exit) or (quit)
``````

Results: Stored in vars 1, 2, 3, an exception in e

user=> (/ 5.0 0.0)
Infinity
user=> (/ (identity 5.0) (identity 0.0))

ArithmeticException Divide by zero clojure.lang.Numbers.divide (Numbers.java:158)
user=>
```