#include <stdio.h>
#include <gsl/gsl_interp.h>
#include <gsl/gsl_spline.h>

int main() {
    // Given data points
    double x[] = {0, 0.5, 0.540675, 0.58015, 0.622, 0.6855, 0.744, 0.867, 0.988, 1.1};
    double y[] = {1.1, 1, 0.93896518, 0.88451263, 0.8392283, 0.78118162, 0.7311828, 0.65397924, 0.5951417, 0.56};
    size_t n = sizeof(x) / sizeof(x[0]);

    // Set up GSL interpolation and spline objects
    gsl_interp_accel *acc = gsl_interp_accel_alloc();
    gsl_spline *spline = gsl_spline_alloc(gsl_interp_cspline, n);

    // Initialize the spline with data points
    gsl_spline_init(spline, x, y, n);

    // Generate points to evaluate the spline
    double x_interp, y_interp;
    for (x_interp = x[0]; x_interp <= x[n - 1]; x_interp += 0.01) {
        y_interp = gsl_spline_eval(spline, x_interp, acc);
        printf("%f %f\n", x_interp, y_interp);
    }

    // Free allocated memory
    gsl_spline_free(spline);
    gsl_interp_accel_free(acc);

    return 0;
}

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Read inputs from stdin

OneCompiler's C online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample C program which takes name as input and print your name with hello.

#include <stdio.h>
int main()
{
    char name[50];
    printf("Enter name:");
    scanf("%s", name);
    printf("Hello %s \n" , name );
    return 0;
    
}

About C

C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition if-else is used.

if(conditional-expression) {
   // code
} else {
   // code
}

You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to if-else-if ladder.

switch(conditional-expression) {    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
...    
    
default:     
 // code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  // code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {  
 // code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

Two types of functions are present in C

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

How to declare a Function

return_type function_name(parameters);

How to call a Function

function_name (parameters)

How to define a Function

return_type function_name(parameters) {  
  //code
}