<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

"Eclipse Public License v1.0" which accompanies this distribution, 

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="GUID-AC99E9ED-2C02-561A-ABA4-DCDD415E8653" xml:lang="en"><title>Math

functions</title><shortdesc>Describes the maths functions used by application programs.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<section id="GUID-965ABD80-2C30-43D1-8F40-7BF573301630"><title>Calling syntax</title> <p>Math functions are designed for

use by application programs which must be able firstly to do the desired calculation

and secondly to handle error conditions arising from the calculations. Thus,

the ANSI-style functions of the form</p> <codeblock id="GUID-C277F9D8-5FDD-5460-B059-DF02E36B4948" xml:space="preserve">double sin(double); // typical declaration</codeblock> <codeblock id="GUID-8A9C44FE-7EDF-59DB-AFE0-B48148CBE0C8" xml:space="preserve">double x=1; // argument

double a; // result

a=sin(x); // typical use</codeblock> <p>are not implemented by the Symbian

software platform. Rather, all functions return error information explicitly.</p> <p>All

functions are provided as static member functions of the <codeph>Math</codeph> class.

This is a convenient packaging mechanism. A typical math function is thus

declared like this:</p> <codeblock id="GUID-C363CF23-CE56-59FA-A4EB-2DA2AD886C0D" xml:space="preserve">class Math

    {

public:

    // ...

    static TInt Sin(TReal &aTrg,const TReal &aSrc);

    // ...

    };</codeblock> <p>and used like this:</p> <codeblock id="GUID-EA13F019-D473-5757-B036-8461BD3B0143" xml:space="preserve">TReal x=1; // argument

TReal a; // result

TInt matherror; // error indication

matherror=Math::ASin(a,x); // get result and error

User::LeaveIfError(matherror); // handle error</codeblock> <p>This syntax

is unusual for those used to the ANSI library. However, the ANSI library functions

are designed for speed, and for users whose programs control the valid range

of the arguments, and can thus reasonably ensure that they are within range.

The <codeph>Math</codeph> class, however, provides direct support to expression

interpreters acting on numbers entered by users. In this context, error checking

is a vital part of the process.</p> <p>In most cases, the same variable may

be used for both argument and result, i.e., <codeph>Math::Sin(x,x)</codeph> will

work as expected, because the function has finished with the argument by the

time the result is written to.</p> </section>

<section id="GUID-8633E2E3-316D-40AE-9F88-77E6CF7FA041"><title>Precision</title> <p>The <codeph>TReal</codeph> type is equated

to <codeph>double</codeph>. With an IEEE754 floating-point implementation,

this gives a range from about 2.225074 × 10<sup>–</sup> <sup>308</sup> to

about 1.797693 × 10<sup>+308</sup>, and an accuracy of 15 decimal places.</p> </section>

<section id="GUID-2D26DDD3-FE18-4D0A-AC10-F445708750BB"><title>Error indications</title> <p>All functions return a standard

error code. </p> </section>