README.md

Common Logarithm

Evaluate the common logarithm.

The common logarithm (logarithm with base 10) is defined for any positive real number as

$$\quad \log_{10} \left( x \right) = y \quad \text{such that} \quad 10^y = x$$

Usage

var log10 = require( '@stdlib/math/base/special/log10' );

log10( x )

Evaluates the common logarithm.

var v = log10( 100.0 );
// returns 2.0

v = log10( 8.0 );
// returns ~0.903

v = log10( 0.0 );
// returns -Infinity

v = log10( Infinity );
// returns Infinity

v = log10( NaN );
// returns NaN

For negative numbers, the common logarithm is not defined.

var v = log10( -4.0 );
// returns NaN

Examples

var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var logEachMap = require( '@stdlib/console/log-each-map' );
var log10 = require( '@stdlib/math/base/special/log10' );

var opts = {
    'dtype': 'float64'
};
var x = discreteUniform( 100, 0, 100, opts );

logEachMap( 'log10(%0.4f) = %0.4f', x, log10 );

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C APIs

Usage

#include "stdlib/math/base/special/log10.h"

stdlib_base_log10( x )

Evaluates the common logarithm.

double out = stdlib_base_log10( 100.0 );
// returns 2.0

out = stdlib_base_log10( 8.0 );
// returns ~0.903

The function accepts the following arguments:

• x: [in] double input value.

double stdlib_base_log10( const double x );

Examples

#include "stdlib/math/base/special/log10.h"
#include <stdlib.h>
#include <stdio.h>

int main() {
    double x;
    double v;
    int i;

    for ( i = 0; i < 100; i++ ) {
        x = ( (double)rand() / (double)RAND_MAX ) * 100.0;
        v = stdlib_base_log10( x );
        printf( "log10(%lf) = %lf\n", x, v );
    }
}

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See Also

• @stdlib/math/base/special/exp10: base 10 exponential function.
• @stdlib/math/base/special/ln: evaluate the natural logarithm of a double-precision floating-point number.
• @stdlib/math/base/special/log: compute the base b logarithm of a double-precision floating-point number.