How to use ln function in c language

The ln function calculates the natural logarithm (base e). Usage: 1. Include the <math.h> header file; 2. Declare a double variable to store the result; 3. Call the ln function and pass the positive real number x; 4. Store the result in the declared variable. Sample code: #include <math.h> int main() { double x = 2.71828; double natural_log = ln(x); printf("The natural logarithm of the natural constant e: %f\n", natural_log); return 0;

#The use of ln function in C language

#ln function is one of the C language mathematics libraries Function that computes the natural logarithm (logarithm to base e). The specific usage is as follows:

Function prototype:

<code class="c">double ln(double x);</code>

Function:

ln function calculates the natural value of a given positive real number x logarithm. The natural logarithm is the logarithm with the natural constant e as its base.

Parameters:

• #x: The positive real number whose natural logarithm is to be calculated.

Return value:

Returns the natural logarithm of x. If x is not a positive real number, NaN (not a number) is returned.

Instructions:

To use the ln function, follow these steps:

1. Contains<math.h> head File.
2. Declare a double type variable in the code to store the result.
3. Call the ln function and pass the real number x whose natural logarithm is to be calculated.
4. Store the result in the declared variable.

Example:

<code class="c">#include <math.h>

int main() {
  double x = 2.71828;  // 自然常数 e
  double natural_log = ln(x);

  printf("自然常数 e 的自然对数：%f\n", natural_log);

  return 0;
}</code>

Running this program will output:

<code>自然常数 e 的自然对数：1.000000</code>

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