CODEWITHSUNDEEP
java
Muhammad Haryadi Futra
Muhammad Haryadi Futra

Reputation: 421

How to calculate logarithms in java?

I'm trying to write a Java program that can take values and put them into a formula involving log 1/3.

How can I calculate log 1/3 in Java?

Upvotes: 6

Views: 42037

Answers (5)

Puspam
Puspam

Reputation: 2777

1/3 yields the result as integer type value. So, the result will be 0, not 0.3333.

Therefore, Math.log(1/3) = Math.log(0), which results in infinity.

So, you need to write Math.log(1/3.0) to get the desired result.

Upvotes: 3

MrTux
MrTux

Reputation: 33993

You can calculate the natural logarithm using the Java.lang.Math.log() method:

System.out.println("Math.log(1/3.0)=" + Math.log(1/3.0));

See http://www.tutorialspoint.com/java/lang/math_log.htm and http://docs.oracle.com/javase/7/docs/api/java/lang/Math.html#log%28double%29

In order to get the log_10 you can do it as follows:

System.out.println("log_10(1/3.0)=" + (Math.log(1/3.0)/Math.log(10)));

Upvotes: 1

Stefan Dollase
Stefan Dollase

Reputation: 4620

When you want to calculate the logarithm you need to know the base. Once you know the base you can perform the calculation:

log_b(x) = ln(x) / ln(b)

http://en.wikipedia.org/wiki/Logarithm#Change_of_base

In Java the Math#log(double) function calculates the natural logarithm. So you can use this to calculate the logarithm to a given base b:

double result = Math.log(x) / Math.log(b);

Upvotes: 8

Akash Thakare
Akash Thakare

Reputation: 22974

You can use Math.log(value) to get log of specific value where value is considered to be in double.You can also use Math.log10(value) to get base 10 log.

So you can just use

Math.log(1/3.0)

Upvotes: 7

Ruchira Gayan Ranaweera
Ruchira Gayan Ranaweera

Reputation: 35547

You don't need a new implementation there is inbuilt function for this

Read about Math.log()

But in this case log(1/3) will give you value as infinity,If you use Math.log(1/3).

You can use log rule as follows.

log(1/3) =log(1)-log(3)

Now

Math.log(1/3)=Math.log(1)-Math.log(3)

Eg:

System.out.println(Math.log(1)-Math.log(3));

Out put:

-1.0986122886681098

Upvotes: 0

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