HP 39g+ Graphing manual Explicit and implicit multiplication, Parentheses

Explicit and implicit multiplication

H I N T

Implied multiplication takes place when two operands appear with no operator in between. If you enter AB, for example, the result is A*B.

However, for clarity, it is better to include the multiplication sign where you expect multiplication in an expression. It is clearest to enter AB as A*B.

Implied multiplication will not always work as expected. For example, entering A(B+4) will not give A*(B+4). Instead an error message is displayed: “Invalid User Function”. This is because the calculator interprets A(B+4) as meaning ‘evaluate function A at the value B+4’, and function A does not exist. When in doubt, insert the * sign manually.

Parentheses

You need to use parentheses to enclose arguments for functions, such as SIN(45). You can omit the final parenthesis at the end of an edit line. The calculator inserts it automatically.

Parentheses are also important in specifying the order of operation. Without parentheses, the hp 39g+ calculates according to the order of algebraic precedence (the next topic). Following are some examples using parentheses.

Entering...								Calculates...
					π			sin (45 + π)
	45
							π	sin (45) + π
	45
								85 ⋅ 9
		85		9
								85 ⋅ 9
			85			9

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