TAking the minimum of three values

[Sona]

I need to find a minimum of three float values.. what would be the most
efficient way of doing this? Can someone please share a #define macro or
something with me for doing this? Thanks

Sona

[Howard]

"Sona" <so**********@n ospam.com> wrote in message
news:3f******** @clarion.carno. net.au...

I need to find a minimum of three float values.. what would be the most
efficient way of doing this? Can someone please share a #define macro or
something with me for doing this? Thanks

Sona

x = min( a, min( b, c ) );

-Howard

[Ron Natalie]

Sona wrote:

I need to find a minimum of three float values.. what would be the most
efficient way of doing this? Can someone please share a #define macro or
something with me for doing this? Thanks

In C++

#include <algoritm>

double min3(double a, double b, double c) {
return std::min(a, std::min(b, c));
}

[Vincent Lascaux]

> #include <algoritm>

double min3(double a, double b, double c) {
return std::min(a, std::min(b, c));
}

To keep the templated aspect of min, you could even write

namespace
{
template<class T>
T& min(T const& a, T const& b, T const& c)
{
return min(a, min(b,c));
}
}

Like that std::min works with any type, and with 2 or 3 arguments

[Steve Zimmerman]

Sona wrote:

I need to find a minimum of three float values.. what would be the most
efficient way of doing this? Can someone please share a #define macro or
something with me for doing this? Thanks

Sona

Sona,

Thank you for your post.

--Steve

#include <stdio.h>

float min(float h, float j);

int main()
{
float a, b, c;

printf("Enter three float values, separated by spaces: ");
scanf("%f%f%f", &a, &b, &c);
/*
* NOTE: I had to round the floats off to two decimal places
* in the following printf statement, because I was getting
* weird errors otherwise.
*/
printf("The minimum of these three is %.2f\n", min(a, min(b, c)));

return 0;
}

float min(float h, float j)
{
if (h < j)
return h;
else
return j;
}

[Irrwahn Grausewitz]

[cross-posting to c.l.c++ fixed]

Steve Zimmerman <st******@sonic .net> wrote:

Sona wrote:

I need to find a minimum of three float values [...]

<SNIP>

Why not make use of the standard C library?
Code modified:

#include <stdio.h>
#include <math.h> /* for fminf() */

int main( void )
{
float a, b, c;

printf("Enter three float values, separated by spaces: ");
scanf("%f%f%f", &a, &b, &c);
printf("The minimum is: %f\n", fminf(a, fminf(b, c)) );

return 0;
}

<SNIP>

--
Close your eyes and press escape three times.

[Peter Nilsson]

"Howard" <al*****@hotmai l.com> wrote in message news:<bj******* *@dispatch.conc entric.net>...

"Sona" <so**********@n ospam.com> wrote in message
news:3f******** @clarion.carno. net.au...

I need to find a minimum of three float values.. what would be the most
efficient way of doing this? Can someone please share a #define macro or
something with me for doing this? Thanks

Sona

x = min( a, min( b, c ) );

Given a typical definition of min(), that will not produce an efficient result.

#define min3(a,b,c) \
( (a) < (b) ? min(a,c) : min(b,c) )

--
Peter

[Martin Ambuhl]

Peter Nilsson wrote:

"Howard" <al*****@hotmai l.com> wrote in message news:<bj******* *@dispatch.conc entric.net>...

x = min( a, min( b, c ) );

Given a typical definition of min(), that will not produce an efficient result.

#define min3(a,b,c) \
( (a) < (b) ? min(a,c) : min(b,c) )

Have you counted the number of evaluations of a or b this involves? There
is a good reason for preferring functions over defines.
--
Martin Ambuhl

[Jirka Klaue]

Irrwahn Grausewitz wrote:

Steve Zimmerman <st******@sonic .net> wrote:

Sona wrote:

I need to find a minimum of three float values [...]

Why not make use of the standard C library?
Code modified:

#include <stdio.h>
#include <math.h> /* for fminf() */

Is this in C89, too? If not, the standard C library provides qsort.
It is not *that* efficient for 3 values, but in return it's scalable.
#include <stdio.h>
#include <stdlib.h>

static int cmp(const void *a, const void *b)
{
return *(float *)a < *(float *)b ? -1 : 1; /* Is 0 really required? */
}

int main( void )
{
float v[] = {2.3, 2.4, 2.299};

qsort(v, sizeof v / sizeof *v, sizeof *v, cmp);
printf("The minimum is: %f\n", *v);

return 0;
}

Jirka

[Irrwahn Grausewitz]

Martin Ambuhl <ma*****@earthl ink.net> wrote:

Peter Nilsson wrote:

#define min3(a,b,c) \
( (a) < (b) ? min(a,c) : min(b,c) )

Have you counted the number of evaluations of a or b this involves? There
is a good reason for preferring functions over defines.

Not to mention possible side effects; consider:

float m3, x, y, z;
m3 = min3( x *= 3.142, y /= 2.718, z += 1.111 );
Irrwahn
--
Computer: a million morons working at the speed of light.