1. c語言中對數函數的表示。。。
"log10(P)"這個寫法對嗎，好像不需要10吧，直接log（p）就可以了。
2. 如何用C語言編寫一個對數運算
直接用函數，調用數學函數即可。記得包涵頭文件
3. C語言中求對數的函數是什麼
求lnx為log(x)求log 10 x是log10(x)沒有專門的求任意底數對數的函數,不過可以用log(x)/log(y)表示log y x
4. C語言如何實現對數運算
庫函數里有對數函數，如，ln，log等，使用時需要包含頭文件math.h
5. c語言 求對數問題，
沒有專門的求任意底數對數的函數,不過可以用 log(x)/log(y)表示log y x
b=log5(sqrt(a));改為b=log(sqrt(a))/log(5);
6. c語言怎樣輸入對數
#include<stdio.h>
#include <math.h>
void main()
{
float x=5,y;
y=log(x);
printf("%f ",y);
}
(6)對數演算法C語言擴展閱讀：
C語言中使用對數函數的方法
log()函數：返回以e為底的對數值
頭文件：
1#include
log() 函數返回以 e 為底的對數值，其原型為：
1doublelog(doublex);
log()用來計算以e為底的 x 的對數值，然後將結果返回。設返回值為 ret，則
1x = eret
如果 x 為負數或 0，則會發生錯誤並設置 errno 值。錯誤代碼：
EDOM：參數x 為負數；
ERANGE：參數x
為零值，零的對數值無定義。
注意：使用 GCC 編譯時請加入-lm。
7. 怎樣用c語言實現對數及其加減乘除的運算
添加頭文件#include "math.h"，聲明雙精度浮點變數，然後調用庫函數log或log10就可以了。如：
#include "stdio.h"
#include "math.h"
void main(void){
double x,sum=0.0;
int i;
for(i=1;i<101;i++)
sum+=log10(i);
printf("%f\n",sum);
x=sum+log(3)/log(2)+log10(7)-log(105)-log10(2)*log10(7);
}
這代碼求出了log1+log2+log3+...+log100的值。而x=sum+log(3)/log(2)+log10(7)-log(105)-log10(2)*log10(7);進行了常用對數(log10)和自然對數(log)的四則運算，並計算結果賦給了雙精度變數x。
8. 請問用C語言怎麼可以實現對數和指數運算
//////////////////////////////////////////////////////////////////////
//
// 對數的例子//
// <filename> : main.cpp
//
// Functions:
//
// exp, log, log10
//////////////////////////////////////////////////////////////////////
#include <iostream> // for i/o functions
#include <valarray> // for valarray
#include <math.h> // for exp(), log(), and log10()
using namespace std;
#define ARRAY_SIZE 3 // array size
typedef valarray<double> DB_VARRAY;
void main()
{
// Set val_array to contain values 1, 10, 100 for the following test.
DB_VARRAY val_array(ARRAY_SIZE);
for (int i = 0; i < ARRAY_SIZE; i++)
val_array[i] = pow(10, i);
// Display the size of val_array.
cout << "Size of val_array = " << val_array.size() << "\r\n";
// Display the content of val_array before calling exp, log, and
// log10 functions.
cout << "The values in val_array:\r\n";
for (i = 0; i < ARRAY_SIZE; i++)
cout << val_array[i] << " ";
cout << "\r\n\r\n";
// rvalue_array to hold the return value from calling the sqrt() and
// pow() functions.
DB_VARRAY rvalue_array;
// ----------------------------------------------------------------
// exp() - display the content of rvalue_array
// ----------------------------------------------------------------
rvalue_array = exp(val_array);
cout << "The result after calling exp():\r\n";
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << "\r\n\r\n";
// ----------------------------------------------------------------
// log() - display the content of rvalue_array
// ----------------------------------------------------------------
rvalue_array = log(val_array);
cout << "The result after calling log():\r\n";
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << "\r\n\r\n";
// ----------------------------------------------------------------
// log10() - display the content of rvalue_array
// ----------------------------------------------------------------
rvalue_array = log10(val_array);
cout << "The result after calling log10():\r\n";
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << "\r\n\r\n";
}
Program Output is:
Size of val_array = 3
The values in val_array:
1 10 100
The result after calling exp():
2.71828 22026.5 2.68812e+043
The result after calling log():
0 2.30259 4.60517
The result after calling log10():
0 1 2
//////////////////////////////////////////////////////////////////////
//
// 指數的例子//
// main.cpp : Illustrates the use of STL sqrt() and pow() functions.
//
// Functions:
//
// sqrt, pow
//////////////////////////////////////////////////////////////////////
#include <iostream> // for i/o functions
#include <valarray> // for valarray
#include <cmath> // for sqrt() and pow()
using namespace std ;
#define ARRAY_SIZE 3 // array size
void main()
{
// Set val_array to contain values 1, 4, 9 for the following test
valarray<double> val_array(ARRAY_SIZE);
for (int i = 0; i < ARRAY_SIZE; i++)
val_array[i] = (i+1) * (i+1);
// Display the size of val_array
cout << "Size of val_array = " << val_array.size() << endl;
// Display the values of val_array before calling sqrt() and pow().
cout << "The values in val_array:" << endl;
for (i = 0; i < ARRAY_SIZE; i++)
cout << val_array[i] << " ";
cout << endl << endl;
// Initialize rev_valarray that is the reverse of val_array.
valarray<double> rev_valarray(ARRAY_SIZE);
for (i = 0; i < ARRAY_SIZE; i++)
rev_valarray[i] = val_array[ARRAY_SIZE - i - 1];
// Display the size of rev_valarray.
cout << "Size of rev_valarray = " << rev_valarray.size() << endl;
// Display the values of rev_valarray.
cout << "The values in rev_valarray:" << endl;
for (i = 0; i < ARRAY_SIZE; i++)
cout << rev_valarray[i] << " ";
cout << endl << endl;
// rvalue_array to hold the return value from calling the sqrt() and
// pow() functions.
valarray<double> rvalue_array;
// ----------------------------------------------------------------
// sqrt() - display the content of rvalue_array
// ----------------------------------------------------------------
// Display the result of val_array after calling sqrt().
rvalue_array = sqrt(val_array);
cout << "The result of val_array after calling sqrt():" << endl;
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << endl << endl;
// ----------------------------------------------------------------
// pow() - display the content of rvalue_array
// ----------------------------------------------------------------
// This template function returns an object of class valarray<T>,
// each of whose elements at I is x[I] raised to the power of y[I].
rvalue_array = pow(val_array, rev_valarray);
cout << "The result after calling pow(val_array, rev_valarray):"
<< endl;
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << endl << endl;
// This template function stores in element I x[I] raised to the
// power of y, where y=2.0.
rvalue_array = pow(val_array, 2.0);
cout << "The result after calling pow(val_array, 2.0):" << endl;
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << endl << endl;
// This template function stores in element I x raised to the
// y[I] power, where x=2.0.
rvalue_array = pow(2.0, val_array);
cout << "The result after calling pow(2.0, val_array):" << endl;
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << endl << endl;
}
Program Output is:
Size of val_array = 3
The values in val_array:
1 4 9
Size of rev_valarray = 3
The values in rev_valarray:
9 4 1
The result of val_array after calling sqrt():
1 2 3
The result after calling pow(val_array, rev_valarray):
1 256 9
The result after calling pow(val_array, 2.0):
1 16 81
The result after calling pow(2.0, val_array):
2 16 512
以上例子全是MSDN的標準例子 , 安裝MSDN吧, 這種問題迎刃而解
9. 在c語言中自然對數怎麼求啊
1、C里直接提供的是 以 e 為底的自然對數 log ,和 以 10 為底的常用對數 log10。
2、常式：
#include<stdio.h>
#include<math.h>
doubleloga(doublen,doublebase);
intmain(void)
{
doublea,b,c;
a=log(exp(1));
b=log10(10);
c=loga(100,5);
printf("%lf%lf%lf",a,b,c);
}
doubleloga(doublen,doublebase)
{returnlog(n)/log(base);}