problem with double data in exponential form

[pereges]

Hi, can anyone please tell me what is wrong in this program and why
does it keep givng nan as the output(eg. take input as 1.2e+10) ?

#include <stdio.h>

#define PLANCK 6.626068e10-34


int main(void)
{
double freq;

printf("Enter frequency");
scanf("%e",&fre q);
double energy = PLANCK * freq;

printf("\n%f", energy);
return 0;

}

[user923005]

Re: problem with double data in exponential form

On Apr 14, 10:44 am, pereges <Brol...@gmail. comwrote:

Hi, can anyone please tell me what is wrong in this program and why
does it keep givng nan as the output(eg. take input as 1.2e+10) ?
>
#include <stdio.h>
>
#define PLANCK 6.626068e10-34
>
int main(void)
{
        double freq;
>
        printf("Enter frequency");
                scanf("%e",&fre q);

foo.c: (in function main)
foo.c(13,28): Format argument 1 to scanf (%e) expects float * gets
double *:

                double energy = PLANCK * freq;
>
                printf("\n%f", energy);
                return 0;
>
>
>
}- Hide quoted text -
>
- Show quoted text -

[user923005]

Re: problem with double data in exponential form

On Apr 14, 10:44 am, pereges <Brol...@gmail. comwrote:

Hi, can anyone please tell me what is wrong in this program and why
does it keep givng nan as the output(eg. take input as 1.2e+10) ?
>
#include <stdio.h>
>
#define PLANCK 6.626068e10-34
>
int main(void)
{
        double freq;
>
        printf("Enter frequency");
                scanf("%e",&fre q);
                double energy = PLANCK * freq;
>
                printf("\n%f", energy);
                return 0;
>
>
>
}- Hide quoted text -
>
- Show quoted text -

P.S.
From the C-FAQ:
12.13: Why doesn't this code:

double d;
scanf("%f", &d);

work?

A: Unlike printf(), scanf() uses %lf for values of type double,
and
%f for float. See also question 12.9.

[Gordon Burditt]

Re: problem with double data in exponential form

>Hi, can anyone please tell me what is wrong in this program and why

>does it keep givng nan as the output(eg. take input as 1.2e+10) ?
>
>#include <stdio.h>
>

Is this really supposed to be a constant slightly different from
6.626068e10 ?

>#define PLANCK 6.626068e10-34

Use parentheses.

> double energy = PLANCK * freq;

This expands to:

double energy = 6.626068e10-34 * freq;
which means:
double energy = (6.626068e10) - (34 * freq);
which I don't think is what you really mean.

I recommend you use at least one pair of unnecessary parentheses:

#define PLANCK (((6.626068e10) - (34)))

[pereges]

Re: problem with double data in exponential form

On Apr 14, 11:05 pm, user923005 <dcor...@connx. comwrote:

P.S.
From the C-FAQ:
12.13: Why doesn't this code:
>
double d;
scanf("%f", &d);
>
work?
>
A: Unlike printf(), scanf() uses %lf for values of type double,
and
%f for float. See also question 12.9.

I changed it to:

double freq;
printf("Enter frequency");
scanf("%lf",&fr eq);
double energy = PLANCK * freq;
printf("\n%e", energy);


getting some negative garbage value now.

[user923005]

Re: problem with double data in exponential form

On Apr 14, 11:11 am, pereges <Brol...@gmail. comwrote:

On Apr 14, 11:05 pm, user923005 <dcor...@connx. comwrote:
>

P.S.
From the C-FAQ:
12.13:  Why doesn't this code:

>

                double d;
                scanf("%f", &d);

>

        work?

>

A:      Unlike printf(), scanf() uses %lf for values of type double,
and
        %f for float.  See also question 12.9.

>
I changed it to:
>
double freq;
printf("Enter frequency");
scanf("%lf",&fr eq);
double energy = PLANCK * freq;
printf("\n%e", energy);
>
getting some negative garbage value now.

From:

http://physics.nist.gov/cgi-bin/cuu/Value?h

static const double planck = 6.62606896e-34;

[user923005]

Re: problem with double data in exponential form

On Apr 14, 11:36 am, user923005 <dcor...@connx. comwrote:

On Apr 14, 11:11 am, pereges <Brol...@gmail. comwrote:
>
>
>
>
>

On Apr 14, 11:05 pm, user923005 <dcor...@connx. comwrote:

>

P.S.
From the C-FAQ:
12.13:  Why doesn't this code:

>

                double d;
                scanf("%f", &d);

>

        work?

>

A:      Unlike printf(), scanf() uses %lf for values of type double,
and
        %f for float.  See also question 12.9.

>

I changed it to:

>

double freq;
printf("Enter frequency");
scanf("%lf",&fr eq);
double energy = PLANCK * freq;
printf("\n%e", energy);

>

getting some negative garbage value now.

>
From:http://physics.nist.gov/cgi-bin/cuu/Value?h
>
static const double planck = 6.62606896e-34;- Hide quoted text -
>
- Show quoted text -

#include <stdio.h>

// Standard value:
static const double planck = 6.62606896e-34;
// 2005 National Physical Laboratory value:
static const double planck2 = 6.62607095e-34;

int main(void)
{
double freq;
double energy;
int converted;

oopsie:
printf("Enter frequency: ");
converted = scanf("%le", &freq);
if (converted == 1) {
energy = planck * freq;
printf("Standar d energy = %20.17g\n", energy);
energy = planck2 * freq;
printf("Alterna tive energy = %20.17g\n", energy);
} else
goto oopsie;
return 0;
}

[Robert Gamble]

Re: problem with double data in exponential form

On Apr 14, 1:44 pm, pereges <Brol...@gmail. comwrote:

Hi, can anyone please tell me what is wrong in this program and why
does it keep givng nan as the output(eg. take input as 1.2e+10) ?
>
#include <stdio.h>
>
#define PLANCK 6.626068e10-34

#define PLANCK 6.626068e-34

int main(void)
{
double freq;
>
printf("Enter frequency");

printf("Enter frequency: ");
fflush(stdout);

scanf("%e",&fre q);

scanf("%le", &freq);

double energy = PLANCK * freq;
>
printf("\n%f", energy);

printf("%e\n", energy);

return 0;
>
}

--
Robert Gamble

[Keith Thompson]

Re: problem with double data in exponential form

[Once again, I've added the attribution line that Gordon Burditt has
deliberately and rudely deleted.]

gordonb.czo5z@b urditt.org (Gordon Burditt) writes:

pereges <Broli00@gmail. comwrites:

>>Hi, can anyone please tell me what is wrong in this program and why
>>does it keep givng nan as the output(eg. take input as 1.2e+10) ?
>>
>>#include <stdio.h>
>>

Is this really supposed to be a constant slightly different from
6.626068e10 ?
>

>>#define PLANCK 6.626068e10-34

>
Use parentheses.

Lack of parentheses isn't the problem. Either this is a typo, or the
OP has misunderstood how scientific notation is represented in C.

The approximage value of Planck's constant is 6.626068 * 10**-34,
where "**" denotes exponentiation. In mathematical texts, this is
generally written as something like:

-34
6.626068 * 10

(That's not going to look right unless you use a fixed-width font.)

Since C needs to be written using fonts that don't support
superscripts, the C notation drops the constant "10" and uses:

6.626068E-34

What the OP wrote, "6.626068e1 0-34", would be interpreted by a
compiler as the floating-point constant 6.626068e10, a "-" operator,
and the integer constant 34, but I'm sure that's not what he intended.

So the correct definition (assuming the value is correct) would be:

#define PLANCK 6.626068e-34

No parentheses are necessary; a floating-point constant is a single
token, and no ambiguity is possible (barring ugly tricks with
token-pasting).

[...]

I recommend you use at least one pair of unnecessary parentheses:
>
#define PLANCK (((6.626068e10) - (34)))

That's just silly; I hope it was deliberately silly.

As always, I do not grant permission to quote this or any other
article I post to Usenet without attribution. Gordon, you're more
than welcome to respond; just leave the attribution lines alone.

--
Keith Thompson (The_Other_Keit h) <kst-u@mib.org>
Nokia
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"