abs question

[Bill Cunningham]

I have a program written with the intention to create a true range
between stocks. I had a program like this before and lost it so I am having
to re-write it. CL means current low, CH current high, PC previous close. My
system tells me abs is in stdlib.h and not just math.h. I don't know if
that's true or not. Anyway abs takes ints and my variables are all doubles.
I will post the code and anyone interested can comment. I hope it explains
itself with my brief explaination. The program takes CH CL and PC in that
order. I inputted 3.86 3.08 3.86 and there was no response. The answer is
..70.

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
double ch, cl, pc, chr, clr, pcr;
if (argc !=4) {
fprintf(stderr, "TR usage error ch cl pc\n");
exit(EXIT_FAILURE);
}
ch = strtod(argv[1], NULL);
cl = strtod(argv[2], NULL);
pc = strtod(argv[3], NULL);
chr = ch - cl;
clr = cl - pc;
pcr = ch - pc;
if (chr > clr && pcr)
printf("%.2f\n", chr);
if (clr > chr && pcr)
printf("%.2f\n", clr);
if (pcr > chr && clr)
printf("%.2f\n", pcr);
return 0;
}

 

[Bill Cunningham]

Oh god. Well never mind I have "discovered" fabs. I guess this is my
answer. I will try it anyway.

Bill

 

[Tim Prince]

..... My
system tells me abs is in stdlib.h and not just math.h. I don't know if
that's true or not. Anyway abs takes ints and my variables are all doubles.

abs() is of type int; fabs() was of type double in C89 <math.h>, it may be
in <tgmath.h> if your compiler has some C99 capability. Most compilers
can generate single instruction in-line implementation of fabs().
It's not difficult to check your "system," the answer would be in the
compiler or library docs, and probably in the header files in the
compiler's include folder.
I don't see a connection with the source code you showed.

 

[Martin Ambuhl]

I have a program written with the intention to create a true range
between stocks. I had a program like this before and lost it so I am having
to re-write it. CL means current low, CH current high, PC previous close. My
system tells me abs is in stdlib.h and not just math.h. I don't know if
that's true or not. Anyway abs takes ints and my variables are all doubles.

so use fabs()

I will post the code and anyone interested can comment. I hope it explains
itself with my brief explaination. The program takes CH CL and PC in that
order. I inputted 3.86 3.08 3.86 and there was no response. The answer is
.70.

Are you sure it isn't 0.80?

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
double ch, cl, pc, chr, clr, pcr;
if (argc !=4) {
fprintf(stderr, "TR usage error ch cl pc\n");
exit(EXIT_FAILURE);
}
ch = strtod(argv[1], NULL);
cl = strtod(argv[2], NULL);
pc = strtod(argv[3], NULL);
chr = ch - cl;
clr = cl - pc;
pcr = ch - pc;
if (chr > clr && pcr)

^^^^^^^^^^^^^^^^^^
This (and the two like it) are probably nonsense. See the version below.

printf("%.2f\n", chr);
if (clr > chr && pcr)
printf("%.2f\n", clr);
if (pcr > chr && clr)
printf("%.2f\n", pcr);
return 0;
}

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
double current_high, current_low, prevous_close, current_range,
low_vs_close, high_vs_close;
if (argc != 4) {
fprintf(stderr, "TR usage error:\n"
"program_name current_high current_low "
"prevous_close\n");
exit(EXIT_FAILURE);
}
current_high = strtod(argv[1], NULL);
current_low = strtod(argv[2], NULL);
prevous_close = strtod(argv[3], NULL);
current_range = current_high - current_low;
low_vs_close = current_low - prevous_close;
high_vs_close = current_high - prevous_close;
if (current_range > low_vs_close && current_range > high_vs_close)
printf("%.2f\n", current_range);
if (low_vs_close > current_range && low_vs_close > high_vs_close)
printf("%.2f\n", low_vs_close);
if (high_vs_close > current_range && high_vs_close > low_vs_close)
printf("%.2f\n", high_vs_close);
return 0;
}

 

[Bill Cunningham]

I don't see a connection with the source code you showed.

The thing is I really don't know where to use fabs in this code. I've
tried it in the printfs, for example,

if (chr > clr && pcr)
printf("%.2f\n", fabs(chr));
if (clr > chr && pcr)
printf("%.2f\n", fabs(clr));
if (pcr > chr && clr)
printf("%.2f\n", fabs(pcr));

This doesn't help. This is a math question. Where to use fabs.

Bill

 

[Bill Cunningham]

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
double current_high, current_low, prevous_close, current_range,
low_vs_close, high_vs_close;
if (argc != 4) {
fprintf(stderr, "TR usage error:\n"
"program_name current_high current_low "
"prevous_close\n");
exit(EXIT_FAILURE);
}
current_high = strtod(argv[1], NULL);
current_low = strtod(argv[2], NULL);
prevous_close = strtod(argv[3], NULL);
current_range = current_high - current_low;
low_vs_close = current_low - prevous_close;
high_vs_close = current_high - prevous_close;
if (current_range > low_vs_close && current_range > high_vs_close)
printf("%.2f\n", current_range);
if (low_vs_close > current_range && low_vs_close > high_vs_close)
printf("%.2f\n", low_vs_close);
if (high_vs_close > current_range && high_vs_close > low_vs_close)
printf("%.2f\n", high_vs_close);
return 0;
}

I think that might just be the answer martin thanks I will
incorporate this into my code.

Bill

 

[Nick Keighley]

    The thing is I really don't know where to use fabs in this code. I've
tried it in the printfs, for example,

if (chr > clr && pcr)
        printf("%.2f\n", fabs(chr));
    if (clr > chr && pcr)
        printf("%.2f\n", fabs(clr));
    if (pcr > chr && clr)
        printf("%.2f\n", fabs(pcr));

This doesn't help. This is a math question. Where to use fabs.

You use fabs() when you want the absolute value of a floating
point number (I can't be bothered to check if fabs() takes
a float or a double).

fabs(1.0) -> 1.0
fabs(-1.0) -> 1.0

I know nothing about finance so I have no idea if you actually
want to calculate fabs or where.

So
- what output did you get?
- what did you expect?

You may have noticed me asking this before...

 

[Richard Tobin]

You use fabs() when you want the absolute value of a floating
point number (I can't be bothered to check if fabs() takes
a float or a double).

fabs() predates prototypes, so it naturally takes a double because
of the default promotions.

-- Richard