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# math with int and floats doesn't work?

 P: n/a I could have sworn this would be a FAQ, but it doesn't appear to be in there. You must get this all the time, or I'm just totally doing something wrong. Math with int's and floats appears to just not work at all, much to my frustration. :-( I'm trying to write a simple calculation and it just plain outputs wrong information. Something like this: function calculateValue(kWh) { dollar_amount = kWh * .033; // dollar_amount = StrS(dollar_amount, 1, 2); result.innerHTML = dollar_amount; } I even jumped through hoops to try to enforce type, and convert strings to float format, but it still doesn't work (which is wierd in itself). function calculateValue(inputValue) { var kWh = new String(inputValue); kWh = parseFloat(kWh); dollar_amount = kWh * .033; dollar_amount = StrS(dollar_amount, 1, 2); result.innerHTML = dollar_amount; } I've seen float errors in calculators, and other languages, but nothing that was just totally wrong everytime by a power of ~10, it's a little insane! Eric Jul 20 '05 #1
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 P: n/a "Eric Gibson" writes: I could have sworn this would be a FAQ, but it doesn't appear to be in there. You must get this all the time, or I'm just totally doing something wrong. If your results are so surpricing, my bet is that you are doing something wrong. Javascript isn't significantly different from other languages in how it handles numbers. Math with int's and floats appears to just not work at all, much to my frustration. :-( I'm *pretty* sure you are doing something wrong then :). I'm trying to write a simple calculation and it just plain outputs wrong information. Something like this: function calculateValue(kWh) { dollar_amount = kWh * .033; // dollar_amount = StrS(dollar_amount, 1, 2); result.innerHTML = dollar_amount; } The three questions that needs answers before anyone can help you: What do you do? What is it supposed to do? What does it do? The first is almost answered by the code, except: Where is it called and with what as an argument? I even jumped through hoops to try to enforce type, and convert strings to float format, but it still doesn't work (which is wierd in itself). The multiplication should convert its other arguments to numbers, similar to using the Number conversion function. function calculateValue(inputValue) { var kWh = new String(inputValue); kWh = parseFloat(kWh); dollar_amount = kWh * .033; dollar_amount = StrS(dollar_amount, 1, 2); result.innerHTML = dollar_amount; } I've seen float errors in calculators, and other languages, but nothing that was just totally wrong everytime by a power of ~10, it's a little insane! I don't know the function StrS, but the rest looks fine. If it is off by a factor of 10, are you sure the input is correct, and that .033 is the correct multiplyer (and it shouldn't have been 0.33)? /L -- Lasse Reichstein Nielsen - lr*@hotpop.com Art D'HTML: 'Faith without judgement merely degrades the spirit divine.' Jul 20 '05 #2

 P: n/a JRS: In article , seen in news:comp.lang.javascript, Eric Gibson posted at Sat, 27 Sep 2003 17:49:16 :- I could have sworn this would be a FAQ, but it doesn't appear to be inthere. You must get this all the time, or I'm just totally doing somethingwrong.Math with int's and floats appears to just not work at all, much to myfrustration. :-( I'm trying to write a simple calculation and it just plainoutputs wrong information. Something like this:function calculateValue(kWh) { dollar_amount = kWh * .033; // dollar_amount = StrS(dollar_amount, 1, 2); result.innerHTML = dollar_amount;} The arithmetic works for me. I trust that you actually supplied the function StrS, and the functions Sign and StrU which it calls. One should never write a number with the first or last character a decimal point, since that is liable to human error. But, assuming that you meant 0.033, that's not your problem; but your electricity is too cheap. For something like this, you should always give a complete "non-working" answer, with data, together with what you wish the function to do and the results that you expect. -- © John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v4.00 IE 4 © Jim Ley's FAQ for news:comp.lang.javascript JS maths, dates, sources. TP/BP/Delphi/JS/&c., FAQ topics, links. Jul 20 '05 #3

 P: n/a JRS: In article , seen in news:comp.lang.javascript, Lasse Reichstein Nielsen posted at Sun, 28 Sep 2003 00:27:06 :-I don't know the function StrS, but the rest looks fine. Even you should read the FAQ ! StrS is also in . -- © John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v4.00 IE 4 © Jim Ley's FAQ for news:comp.lang.javascript JS maths, dates, sources. TP/BP/Delphi/JS/&c., FAQ topics, links. Jul 20 '05 #4

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