Sqrt domain error c builder

Sqrt domain error c builder

Группа: Участник
Сообщений: 9

Люди помогите пожалуйсто.
Есть такой код:

Если выражение под корнем

то возникает ошибка программы с текстом:
SQRT: DOMAIN error,
а затем
ACOS: DOMAIN error.

Как можно подавить эти сообщения. Необходимо, что бы программа не обращала внимание на эти ошибки. Георгий

Отправлено: 19.04.2005, 23:25

Группа: Модератор
Сообщений: 874

пара try catch не помогает? FataLL

Отправлено: 20.04.2005, 02:53

Группа: Участник
Сообщений: 37

Блин, а просто

не канает? Дожили.

Отредактировано FataLL — 20/04/2005, 02:53 ozx

Отправлено: 20.04.2005, 09:51

Группа: Участник
Сообщений: 9

пробовал

Но все равно, ошибки возникают. Может я что-то ни то делаю.

А по-поводу второго варианта, это второе что мне пришло в голову, после try catch, Но я хочу понять, почему, ошибки не подавляются.

Возможно это из-за того что в блоке try я разместил много формул. Хотя я сомневаюсь. FataLL

Отправлено: 21.04.2005, 11:40

Группа: Участник
Сообщений: 37

Копни здесь попробуй:

exp(x) , exp2(x) , expm1(x)

log(x) , log10(x) , log2(x)

x != 0 && !isinf(x) && !isnan(x)

scalbn(x, n) , scalbln(x, n)

x > 0 || (x == 0 && y > 0) ||
( x is an integer)

x != 0 && ! ( x is an integer)

fmod(x, y) , remainder(x, y) ,
remquo(x, y, quo)

nextafter(x, y) ,
nexttoward(x, y)

Domain and Pole Checking

The most reliable way to handle domain and pole errors is to prevent them by checking arguments beforehand, as in the following exemplar:

Range Checking

Programmers usually cannot prevent range errors, so the most reliable way to handle them is to detect when they have occurred and act accordingly.

The exact treatment of error conditions from math functions is tedious. The C Standard, 7.12.1 [ISO/IEC 9899:2011], defines the following behavior for floating-point overflow:

A floating result overflows if the magnitude of the mathematical result is finite but so large that the mathematical result cannot be represented without extraordinary roundoff error in an object of the specified type. If a floating result overflows and default rounding is in effect, then the function returns the value of the macro HUGE_VAL , HUGE_VALF , or HUGE_VALL according to the return type, with the same sign as the correct value of the function; if the integer expression math_errhandling & MATH_ERRNO is nonzero, the integer expression errno acquires the value ERANGE ; if the integer expression math_errhandling & MATH_ERREXCEPT is nonzero, the «overflow» floating-point exception is raised.

It is preferable not to check for errors by comparing the returned value against HUGE_VAL or 0 for several reasons:

• These are, in general, valid (albeit unlikely) data values.
• Making such tests requires detailed knowledge of the various error returns for each math function.
• Multiple results aside from HUGE_VAL and 0 are possible, and programmers must know which are possible in each case.
• Different versions of the library have varied in their error-return behavior.

It can be unreliable to check for math errors using errno because an implementation might not set errno . For real functions, the programmer determines if the implementation sets errno by checking whether math_errhandling & MATH_ERRNO is nonzero. For complex functions, the C Standard, 7.3.2, paragraph 1, simply states that «an implementation may set errno but is not required to» [ISO/IEC 9899:2011].

The obsolete System V Interface Definition (SVID3) [UNIX 1992] provides more control over the treatment of errors in the math library. The programmer can define a function named matherr() that is invoked if errors occur in a math function. This function can print diagnostics, terminate the execution, or specify the desired return value. The matherr() function has not been adopted by C or POSIX, so it is not generally portable.

The following error-handing template uses C Standard functions for floating-point errors when the C macro math_errhandling is defined and indicates that they should be used; otherwise, it examines errno :

See FLP03-C. Detect and handle floating-point errors for more details on how to detect floating-point errors.

Subnormal Numbers

A subnormal number is a nonzero number that does not use all of its precision bits [ IEEE 754 2006 ]. These numbers can be used to represent values that are closer to 0 than the smallest normal number (one that uses all of its precision bits). However, the asin() , asinh() , atan() , atanh() , and erf() functions may produce range errors, specifically when passed a subnormal number. When evaluated with a subnormal number, these functions can produce an inexact, subnormal value, which is an underflow error. The C Standard, 7.12.1, paragraph 6 [ISO/IEC 9899:2011], defines the following behavior for floating-point underflow:

The result underflows if the magnitude of the mathematical result is so small that the mathematical result cannot be represented, without extraordinary roundoff error, in an object of the specified type. If the result underflows, the function returns an implementation-defined value whose magnitude is no greater than the smallest normalized positive number in the specified type; if the integer expression math_errhandling & MATH_ERRNO is nonzero, whether errno acquires the value ERANGE is implementation-defined; if the integer expression math_errhandling & MATH_ERREXCEPT is nonzero, whether the ‘‘underflow’’ floating-point exception is raised is implementation-defined.

Implementations that support floating-point arithmetic but do not support subnormal numbers, such as IBM S/360 hex floating-point or nonconforming IEEE-754 implementations that skip subnormals (or support them by flushing them to zero), can return a range error when calling one of the following families of functions with the following arguments:

• fmod ((min+subnorm), min)
• remainder ((min+ subnorm ), min)
• remquo ((min+ subnorm ), min, quo)

where min is the minimum value for the corresponding floating point type and subnorm is a subnormal value.

If Annex F is supported and subnormal results are supported, the returned value is exact and a range error cannot occur. The C Standard, F.10.7.1 [ISO/IEC 9899:2011], specifies the following for the fmod() , remainder() , and remquo() functions:

When subnormal results are supported, the returned value is exact and is independent of the current rounding direction mode.

Annex F, subclause F.10.7.2, paragraph 2, and subclause F.10.7.3, paragraph 2, of the C Standard identify when subnormal results are supported.

Noncompliant Code Example ( sqrt() )

This noncompliant code example determines the square root of x :

However, this code may produce a domain error if x is negative.

Compliant Solution ( sqrt() )

Because this function has domain errors but no range errors, bounds checking can be used to prevent domain errors:

Noncompliant Code Example ( sinh() , Range Errors)

This noncompliant code example determines the hyperbolic sine of x :

This code may produce a range error if x has a very large magnitude.

Compliant Solution ( sinh() , Range Errors)

Because this function has no domain errors but may have range errors, the programmer must detect a range error and act accordingly:

Noncompliant Code Example ( pow() )

This noncompliant code example raises x to the power of y :

This code may produce a domain error if x is negative and y is not an integer value or if x is 0 and y is 0. A domain error or pole error may occur if x is 0 and y is negative, and a range error may occur if the result cannot be represented as a double .

Compliant Solution ( pow() )

Because the pow() function can produce domain errors, pole errors, and range errors, the programmer must first check that x and y lie within the proper domain and do not generate a pole error and then detect whether a range error occurs and act accordingly:

Noncompliant Code Example ( asin() , Subnormal Number)

This noncompliant code example determines the inverse sine of x :

Compliant Solution ( asin() , Subnormal Number)

Because this function has no domain errors but may have range errors, the programmer must detect a range error and act accordingly:

Risk Assessment

Failure to prevent or detect domain and range errors in math functions may cause unexpected results.

Источник

Adblock
detector

Нравится ресурс? Помоги проекту!

[ Script execution time: 0,0579 ]   [ 16 queries used ]   [ Generated: 10.02.23, 03:04 GMT ]