shadowing a parameter

[wuzertheloser]

Write a program which calculates the integral of the function

f(x)=(A*x^m)/n!

on the interval from a to b (0<a<b). In the main program, scanf
a double value for m and a non-negative integer value for n,
a double value of A, and positive double values for a and b>a.
Call the function Intgr() to evaluate the integral.

Your main program should be followed by three functions:

double Intgr(double m, int n, double A, double a, double b)

double func(double x, double m, int n, double A)

double nfact(int n)


When writing the function Intgr(), use the program w4-10.c
or the program from part B of your hw5, appropriately modified
to integrate an arbitrary function f(x) from a to b
(let the program ask you for n_trap only once, and scan
sufficiently large value for n_trap). Within Intgr() call another
function func() to specify f(x). The return value of func() should
be equal to A*x^m if n=0, or A*x^m/n! if n>0. To evaluate n! call the
function nfact() that you will also write. To evaluate x^m call
the function pow() already embedded in the math.h library.

............... ............... ............... ............... ....

Your output should look like this:

Enter the exponents (double)m and (int)n in f(x)=A*x^m/n! : 3.25 5

Enter the coefficient A in f(x)=A*x^m/n! : -1.5

Enter the bounds for the integration interval, a < b : 1.5 3.75

Integrate f(x) on [a,b]
Enter the number of trapezoids: 1000

The value of the integral is -0.792905 .

*/

#include <stdio.h>
#include <math.h>
double Intgr(double m, int n, double A, double a, double b);
double func(double x, double m, int n, double A);
double nfact(int n);
main()
{
double m, A, a, b, x, del_x, sum, f;
int n, k, n_trap;
printf("Enter the exponents (double)m and (int)n in f(x) = A*x^m/n! : ");
scanf("%f %d", &m, &n);
printf("\nEnter the coefficient A in f(x) = A*x^m/n! : ");
scanf("%f", &A);
printf("\nEnter the bounds for the integration interval, a < b : ");
scanf("%f %f", &a, &b);


printf("Integrate f(x) on [a,b]\n");
printf("Enter the number of trapezoids : ");
scanf("%d", &n_trap);
printf("\nn! is : %g\n", nfact(n));
printf("\nThe value of the integral is %g\n", Intgr(m,n,A,a,b));
}

double Intgr(double m, int n, double A, double a, double b)
{
double m, A, a, b;
int n;
del_x = (b-a)/n_trap;
x = a;
f = A*pow(x,m)/nfact(n);
sum = -0.5 * f;
double m, A, a, b;
int n;
del_x = (b-a)/n_trap;
x = a;
f = A*pow(x,m)/nfact(n);
sum = -0.5 * f;
for(k=0; k<=n_trap; k++)
{
x = k * del_x;
f = A*pow(x,m)/nfact(n);
sum +=f;
}
sum -= 0.5 * f;
sum *= del_x;
}

double func(double x, double m, int n double A)
{
double x, m, A;
int n;
if(n==0) return A*pow(x,m);
else return (A*pow(x,m))/nfact(n);
}

double nfact(int n)
{
if(n==1)return 1;
else return n*nfact(n-1);
}

everytime i compile, i get these error messages:

iacs5.ucsd.edu% !g
gcc hw7.c -lm
hw7.c: In function `Intgr':
hw7.c:77: warning: declaration of `m' shadows a parameter
hw7.c:77: warning: declaration of `A' shadows a parameter
hw7.c:77: warning: declaration of `a' shadows a parameter
hw7.c:77: warning: declaration of `b' shadows a parameter
hw7.c:78: warning: declaration of `n' shadows a parameter
hw7.c:79: error: `del_x' undeclared (first use in this function)
hw7.c:79: error: (Each undeclared identifier is reported only once
hw7.c:79: error: for each function it appears in.)
hw7.c:79: error: `n_trap' undeclared (first use in this function)
hw7.c:80: error: `x' undeclared (first use in this function)
hw7.c:81: error: `f' undeclared (first use in this function)
hw7.c:82: error: `sum' undeclared (first use in this function)
hw7.c:83: error: `k' undeclared (first use in this function)
hw7.c: At top level:
hw7.c:93: error: parse error before "double"
hw7.c: In function `func':
hw7.c:94: error: number of arguments doesn't match prototype
hw7.c:54: error: prototype declaration
iacs5.ucsd.edu% vi hw7.c
Version SVR4.0, Solaris 2.5.0
"hw7.c" 105 lines, 2783 characters

[sicarie]

First of all, in double func() you need a comma between the last two variables you are passing it. I also don't think you should be redeclaring the amounts you are passing to it.

It's the same thing with Intgr() and from there, you should be able to debug from the output statements (gets you down to about 15, but they look manageable at first glance - but let us know if you start having trouble with them).

[momotaro]

this is ur code corrected!
pay attention to redeclaration NO NEED!
PS: dont pay attention to the 3 warnings that u will have! ;)

#include <stdio.h>
#include <math.h>
double Intgr(m, n, A, a, b);
double func(x, m, n, A);
double nfact(n);
double m, A, a, b, x, del_x, sum, f;
int n, k, n_trap;
main()
{
printf("Enter the exponents (double)m and (int)n in f(x) = A*x^m/n! : ");
scanf("%f %d", &m, &n);
printf("\nEnter the coefficient A in f(x) = A*x^m/n! : ");
scanf("%f", &A);
printf("\nEnter the bounds for the integration interval, a < b : ");
scanf("%f %f", &a, &b);


printf("Integrate f(x) on [a,b]\n");
printf("Enter the number of trapezoids : ");
scanf("%d", &n_trap);
printf("\nn! is : %g\n", nfact(n));
printf("\nThe value of the integral is %g\n", Intgr(m,n,A,a,b));
}

double Intgr(double m, int n, double A, double a, double b)
{
del_x = (b-a)/n_trap;
x = a;
f = A*pow(x,m)/nfact(n);
sum = -0.5 * f;
del_x = (b-a)/n_trap;
x = a;
f = A*pow(x,m)/nfact(n);
sum = -0.5 * f;
for(k=0; k<=n_trap; k++)
{
x = k * del_x;
f = A*pow(x,m)/nfact(n);
sum +=f;
}
sum -= 0.5 * f;
sum *= del_x;
}

double func(double x, double m, int n, double A)
{
if(n==0) return A*pow(x,m);
else return (A*pow(x,m))/nfact(n);
}

double nfact(int n)
{
if(n==1)return 1;
else return n*nfact(n-1);
}

[momotaro]

plz mention ur compiler next time !
thx!

[wuzertheloser]

okay, thanks for the help everyone! i appreciate it =] i'll let you know how everything goes.

i'm not quite sure which compiler i'm using because it comes from my professor's website.

the program is called
SSH secure shell
and it uses vi editor to make the C files. not sure if that helps.

[wuzertheloser]

oh just for clarification
what does the function
double Intgr() output?

i need it to output the sum, but i don't think it's doing that.

[wuzertheloser]

program works fine now
only problem is the output i get for the integral

my output:

Enter the exponents (double)m and (int)n in f(x) = A*x^m/n! : 3.25 5

Enter the coefficient A in f(x) = A*x^m/n! : -1.5

Enter the bounds for the integration interval, a < b : 1.5 3.75

Integrate f(x) on [a,b]
Enter the number of trapezoids : 1000

The value of the integral is -5.87171e+151

correct output:

Enter the exponents (double)m and (int)n in f(x)=A*x^m/n! : 3.25 5

Enter the coefficient A in f(x)=A*x^m/n! : -1.5

Enter the bounds for the integration interval, a < b : 1.5 3.75

Integrate f(x) on [a,b]
Enter the number of trapezoids: 1000

The value of the integral is -0.792905 .


I think this has something to do in my Intgr function correct?

[momotaro]

u r right! ;)
good luck!

[wuzertheloser]

any idea how you would integrate
A*x^m/n! ?

mathematically i know how to do it. but the only inputs i'm allowed to have are A, m, and n. Therefore, x would have no defined value.

[REICC]

I think it has to do with something in the first part. Any suggestions, guys?

[REICC]

also, why are you declaring the variables before main? Sorry, I am a noob

[seforo]

Any function that is defined below the main function should have its function prototype declared before the main function. Otherwise you should define (or write) all your functions before defining main function.