How to use log function in S9S12GA240 controller

punithb — Mon, 08 Aug 2016 05:33:41 GMT

Hi All,

I need to use ln function to read NTC sensor readings. if i use log(number , 2.71828182846) which yields to ln(number). but log function giving wrong value. Could you please tell how to log function in this controller.

Re: How to use log function in S9S12GA240 controller

lama — Mon, 08 Aug 2016 09:31:44 GMT

Hi,

The CodeWarriror IDE help says:

#include <math.h>

double log (double x);

float logf(float x);

Description

log() computes the natural logarithm of x.

Return

ln(x), if x is greater than zero. If x is smaller then zero, NAN is returned; if it is equal to zero, log() returns negative infinity. In both cases, errno is set to EDOM.

So you should be sure:

The function uses correct types.
You have included math.h. and you have used correct function logf, log.
You have opened project with floating point arithmetics support. (ansib.lib should be visible in the Libs directory in project window)

#include <hidef.h>

#include "derivative.h"

#include <math.h>

int a;

volatile float y;

void main(void)

{

for(;;)

{

for ( a=100; a<10000; a+=100)

{

y = logf( a );

asm nop;

}

A full example project is attached.

Best regards,

Ladislav

topic Re: How to use log function in S9S12GA240 controller in S12 / MagniV Microcontrollers

How to use log function in S9S12GA240 controller

Re: How to use log function in S9S12GA240 controller