Question

How to use log1p() function to calculate natural base e logarithm of 1 + argument in PHP

Answer 1

echo "log1p(1) = " . log1p(1) . "<br />";    
echo "log1p(0) = " . log1p(0) . "<br />";
echo "log1p(-0) = " . log1p(-0) . "<br />";
echo "log1p(5) = " . log1p(5) . "<br />";
echo "log1p(100) = " . log1p(100) . "<br />";
echo "log1p(125) = " . log1p(125) . "<br />";    
echo "log1p(125) / log1p(5) = " . log1p(125) / log1p(5) . "<br />";
echo "log1p(3.5) = " . log1p(3.5) . "<br />";
echo "log1p(1000) = " . log1p(1000) . "<br />";
echo "log1p(0.001) = " . log1p(0.001) . "<br />";


/*
run: 

log1p(1) = 0.69314718055995
log1p(0) = 0
log1p(-0) = 0
log1p(5) = 1.7917594692281
log1p(100) = 4.6151205168413
log1p(125) = 4.8362819069515
log1p(125) / log1p(5) = 2.6991803252672
log1p(3.5) = 1.5040773967763
log1p(1000) = 6.9087547793152
log1p(0.001) = 0.00099950033308342

*/

 

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