**Important:**
The information in this document is obsolete and should not be used for new development.

**Inside Macintosh:****QuickDraw GX Environment and Utilities**/**Chapter 8 - QuickDraw GX Mathematics**/**Using QuickDraw GX Mathematics**

## Performing Fixed-Point Operations

You can use QuickDraw GX functions to provide operations on`Fixed`

,`long`

,`fract`

and`wide`

numbers. The equivalent QuickDraw GX fixed-point functions for functions in the Macintosh Mathematical Utilities is shown in Table 8-2.The Macintosh Mathematical Utilities are described in

Inside Macintosh: Operating System Utilities.Some functions combine multiple functions into a single function to increase calculation speed over that obtained using sequential function calls. For example, the

`FractSineCosine`

function returns both the sine and cosine of an angle.Some functions support the use of 64-bit numbers to increase the accuracy of calculations. For example, the

`WideAdd`

function returns the 64-bit sum of two 64-bit numbers, and the`WideDivide`

function returns the quotient of a 64-bit number and a 32-bit number. The`MultiplyDivide`

function uses a 64-bit intermediate result to increase accuracy of the calculation and to prevent premature overflow.The

`MultiplyDivide`

,`Magnitude`

, and`VectorMultiplyDivide`

functions are derivatives of other functions. For example,`MultiplyDivide (x, y, z)`

is the same as:

wide temp; WideDivide (WideMultiply(x, y, &temp), z, 0)The final argument of 0 specifies that the returned number will be rounded with no remainder.You can use the

`Magnitude`

function to determine the magnitude (length) of a two-dimensional vector, or the distance between two points on a plane. Figure 8-18 shows the use of function parameters`deltaX`

and`deltaY`

.

Figure 8-18 Determining the length of a line with the`Magnitude`

function

Functions that provide arithmetic operations on fixed-point numbers are described in the section "Fixed-Point Operations" beginning on page 8-42. Functions that provide operations on

`wide`

numbers are described in the section "Operations on wide Numbers" beginning on page 8-49. The`Magnitude`

function is described on page 8-45.

7 JUL 1996