The log1p() function takes an argument x and returns the natural logarithm of the base-e logarithm of x+1. Here e is a mathematical constant with value equal to 2.71828.
Syntax:
double log1p (double x);
float log1p (float x);
long double log1p (long double x);
Parameter:
- The log1p() function takes a single argument in the range [-1, ?].
- If we pass the value which is less than -1, log1p() returns Nan (Not a Number).
Return:
- a positive number : if x > 0
- zero if x=0
- a negative number if -1 > x > 0
- -?(- infinity) if x=-1
- NaN if x<-1
Error and Exception:
- It is mandatory to give both the arguments otherwise it will give error no matching function for call to ‘log1p()’.
- If we pass the string as argument we will get error no matching function for call to ‘log1p(const char [n]).
- It gives -inf if we pass -1.
- It gives zero if we pass 0.
Examples:
Input : log1p(50.35)
Output : 3.93866
Input : log1p(143)
Output : 4.96981
# CODE 1
CPP
#include <cmath>
#include <iostream>
using namespace std;
int main()
{
double x = 50.35, answer;
answer = log1p(x);
cout << "log1p(" << x << ") = "
<< answer << endl;
return 0;
}
|
Output:
log1p(50.35) = 3.93866
Time Complexity: O(1)
Space Complexity: O(1)
# CODE 2
CPP
#include <cmath>
#include <iostream>
using namespace std;
int main()
{
double answer;
int x = 143;
answer = log1p(x);
cout << "log1p(" << x << ") = "
<< answer << endl;
return 0;
}
|
Output:
log1p(143) = 4.96981
Time Complexity:O(1)
Space Complexity: O(1)
Practical usage:
- It is practically used to get logarithm value of given argument+1.
Last Updated :
06 Feb, 2023
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