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PODecimalFormat the answer?
 

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    <p>Please forgive my ignorance, I'm a beginner.</p> <p>Can anyone tell me why I am getting my error code in the if/else statement below? I think my result for the ln multiplication is is not exactly the same as the standard multiplication (there is a .00000000006 of a difference or something like that). Is there a work around for this? I have tried to use DecimalFormat but to no avail. </p> <p>If I add:</p> <pre><code>DecimalFormat fmt = new DecimalFormat ("0.###"); </code></pre> <p>to the tester and </p> <pre><code> if (fmt.format(z) != fmt.format(result)){ </code></pre> <p>to the if statement I receive my own same error statement. What is wrong!?</p> <p>Thank you very much.</p> <p>Joe</p> <pre><code>import java.util.Scanner; import java.lang.Math; import java.text.DecimalFormat; public class Logs { //integer x field &amp; encapsulation private static double x; // x encapsulation public double getX(){ return x; } public void setX (double ex){ if (ex &gt;= 0){ x = ex; } else{ System.out.println("You may not choose a negative number, 'x' = 0"); } } //integer y field private static double y; // y encapsulation public double getY(){ return y; } public void setY (double why){ if (why &gt;= 0){ y = why; } else{ System.out.println("You may not choose a negative number, 'y' = 0"); } } //tester public static void main (String [] args){ Logs sample =new Logs(); Scanner var = new Scanner(System.in); DecimalFormat fmt = new DecimalFormat ("0.###"); sample.setX (var.nextDouble()); sample.setY (var.nextDouble()); x = sample.getX(); y = sample.getY(); double z = (x*y); double logX = Math.log(y); double logY = Math.log(x); double logZ = (logX +logY); double result = (Math.exp(logZ)); if (z != result){ System.out.printf("%s", "Incorrect answer: be a better coder"); } else { System.out.printf("%s %.3d %s %.3d %s %.3d", "The product of the values you chose is: ", + z, "\nln(x) + ln(y) is: ", + logZ, "\nCompute to e: ", + result); } } } </code></pre>
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    1. USAziz Shaikh
    1. USJoe Austin
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    1. COyou always have to compare Strings using `equals()`.
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      1. USjlordo
    2. COsee http://stackoverflow.com/questions/14749647/why-the-result-of-0-3-3-is-0-89999999999999-in-scala-language for example :)
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    3. COYou're comparing strings with `==`. See http://tinyurl.com/so-java-string-equality
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      1. USJon Skeet
 

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