Artihmetic

Smojo has two kinds of numbers, integers and reals. Integers represent whole numbers, including negative numbers. Reals represent both whole and fractional numbers.

For performance reasons, Smojo has a separate version of arithmetic words for integers and reals:

Word Action

+ - * / =

Used to operate between integers only. If a real number is encountered, it is truncated -- fractional part is discarded. For example,
1 2 +
will give 3 as expected, but
1 2.8 +
will also give 3, since 2.8 is truncated. The equal sign is used to test if two integers on the stack are equal.

+. -. *. /. =.

As above, but these can operate on real numbers. No truncation is performed.

> >= < <=

Inequality tests. These work on both integers and reals. The result is a boolean (TRUE/FALSE) on the stack.
1 2.2 < .
displays
true ok

Word	Action
+ - * / =	Used to operate between integers only. If a real number is encountered, it is truncated -- fractional part is discarded. For example, 1 2 + will give 3 as expected, but 1 2.8 + will also give 3, since 2.8 is truncated. The equal sign is used to test if two integers on the stack are equal.
+. -. *. /. =.	As above, but these can operate on real numbers. No truncation is performed.
> >= < <=	Inequality tests. These work on both integers and reals. The result is a boolean (TRUE/FALSE) on the stack. 1 2.2 < . displays true ok

Examples

	2 3 / . 
	0 ok

	2 3 /. . 
	0.6666666666666666 ok

	1 0.1 / 
	ERROR: / by zero

	1 2.1 / . 
	0 ok

	2.9 1 / . 
	2 ok

	1 2 = . 
	false ok

Quiz

Do you understand the examples above? Can you explain why the program:

		1 2.1 / .

results in 0 being displayed as the answer rather than 0.4761904762, which is what you would have expected with a calculator? What changes would you make to obtain the desired answer?

		1 2.1 /  .
		0 ok

		1 2.1 /. .
		0.47619047619047616 ok

When using

, 2.1 is truncated into 2. The result 0.5 is also truncated, thus 0 is displayed.
When using

/.

, no truncation is preformed.

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