Hello guys. I'm having some problems when compiling some C programs. I can't troubleshoot them since I'm not very proficient with C. But it seems that this error comes from the math.h library, maybe the include is different for Linux.(adsbygoogle = window.adsbygoogle || []).push({});

This is the error i'm getting:

Kareem@Kareem:~/prog/secant$ cc main.c

/tmp/cciW3fYU.o(.text+0x219): In function `F':

: undefined reference to `cos'

collect2: ld returned 1 exit status

this is the code:

Code (Text):/*

* SECANT ALGORITHM 2.4

*

* To find a solution to the equation f(x) = 0

* given initial approximations p0 and p1:

*

* INPUT: initial approximation p0, p1; tolerance TOL;

* maximum number of iterations N0.

*

* OUTPUT: approximate solution p or

* a message that the algorithm fails.

*

*/

#include<stdio.h>

#include<math.h>

#define true 1

#define false 0

main()

{

double P0,F0,P1,F1,P,FP,TOL;

int I,NO,OK,FLAG;

FILE *OUP[1];

double absval(double);

double F(double);

void INPUT(int *, double *, double *, double *, int *);

void OUTPUT(FILE **, int *);

INPUT(&OK, &P0, &P1, &TOL, &NO);

if (OK) {

OUTPUT(OUP, &FLAG);

/* STEP 1 */

I = 2;

F0 = F(P0);

F1 = F(P1);

OK = true;

/* STEP 2 */

while ((I<=NO) && OK) {

/* STEP 3 */

/* compute P(I) */

P = P1 - F1 * (P1 - P0) / (F1 - F0);

/* STEP 4 */

FP = F(P);

if (FLAG == 2) fprintf(*OUP,"%3d %15.8e %15.8e \n",I,P,FP);

if (absval(P - P1) < TOL) {

/* procedure completed successfully */

fprintf(*OUP,"\nApproximate solution P = %12.8f\n",P);

fprintf(*OUP,"with F(P) = %12.8f\n",FP);

fprintf(*OUP,"Number of iterations = %3d",I);

fprintf(*OUP," Tolerance = %14.8e\n",TOL);

OK = false;

}

else {

/* STEP 5 */

I++;

/* STEP 6 */

/* update P0, F0, P1, F1 */

P0 = P1;

F0 = F1;

P1 = P;

F1 = FP;

}

}

if (OK) {

/* STEP 7 */

/* procedure completed unsuccessfully */

fprintf(*OUP,"\nIteration number %3d",NO);

fprintf(*OUP," gave approximation %12.8f\n",P);

fprintf(*OUP,"F(P) = %12.8f not within tolerance : %15.8e\n",FP,TOL);

}

fclose(*OUP);

}

return 0;

}

/* Change function F for a new problem */

double F(double X)

{

double f;

f = cos(X) - X;

return f;

}

void INPUT(int *OK, double *P0, double *P1, double *TOL, int *NO)

{

char AA;

printf("This is the Secant Method.\n");

printf("Has the function F been created in the program immediately preceding\n");

printf("the INPUT function?\n");

printf("Enter Y or N\n");

scanf("%c",&AA);

if ((AA == 'Y') || (AA == 'y')) {

*OK = false;

while (!(*OK)) {

printf("Input initial approximations P0 and P1 separated by blank\n");

scanf("%lf %lf", P0, P1);

if (*P0 == *P1) printf("P0 cannot equal P1\n");

else *OK = true;

}

*OK = false;

while(!(*OK)) {

printf("Input tolerance\n");

scanf("%lf", TOL);

if (*TOL <= 0.0) printf("Tolerance must be positive\n");

else *OK = true;

}

*OK = false;

while (!(*OK)) {

printf("Input maximum number of iterations - no decimal point\n");

scanf("%d", NO);

if (*NO <= 0) printf("Must be positive integer\n");

else *OK = true;

}

}

else {

printf("The program will end so that the function F can be created\n");

*OK = false;

}

}

void OUTPUT(FILE **OUP, int *FLAG)

{

char NAME[30];

printf("Select output destination\n");

printf("1. Screen\n");

printf("2. Text file\n");

printf("Enter 1 or 2\n");

scanf("%d", FLAG);

if (*FLAG == 2) {

printf("Input the file name in the form - drive:name.ext\n");

printf("For example: A:OUTPUT.DTA\n");

scanf("%s", NAME);

*OUP = fopen(NAME, "w");

}

else *OUP = stdout;

printf("Select amount of output\n");

printf("1. Answer only\n");

printf("2. All intermeditate approximations\n");

printf("Enter 1 or 2\n");

scanf("%d", FLAG);

fprintf(*OUP,"Secant Method\n");

if (*FLAG == 2) fprintf(*OUP, " I P F(P)\n");

}

/* Absolute Value Function */

double absval(double val)

{

if (val >= 0) return val;

else return -val;

}

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# [c] <math.h>

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