- #1
DrKareem
- 101
- 1
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.
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:
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:
/*
* 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;
}