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 01172012, 11:58 AM #21Moderator
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Re: Method for calculation Cauchy Inequality with fully implemented handler
Defensive programming is based around you writing code to protect you from methods you call.
In this case you are writing the method itself, in which an illegal argument should throw an IllegalArgument exception...it is, after all, illegal.
Then, should the exception occur in testing, you should try and figure out why you let an IllegalArgument get into this method...
NaN is just as bad. The caller still has to check.
It is the equivalent of returning null on an error.
That is poor practice.
If a method expects arguments of a certain range (and the example given implied that was the case) then arguments outside that range should be classed as illegal. Testing should (and the aforementioned defensive programming) ensure these exceptions do not occur. If they do then fix the source of the problem.
 01172012, 03:40 PM #22Member
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Re: Method for calculation Cauchy Inequality with fully implemented handler
Another method for cosecant calculation here I did not use catch blocks.
Input checking logics throws exceptions.
Java Code:public static double cosecantApprox(double value) throws IllegalArgumentException , ArithmeticException{ double x = value; int i,j,k; int l = 0; int exp = 0; double term = 1/x; double cosecant = 0f; int factor = 0; double sum = 0f; double[] pow = new double[12]; double[] csc = new double[12]; double[] coeff = { 0.16666666666666666666666666666667, 0.01944444444444444444444444444444, 0.00205026455026455026455026455026, 0.00104993386243382043650793650794, 2.3469650205761316872418595679012e5, 7.1224535923609997684043268331463e7, 1.5661391322766984136380961777787e8, 2.609753939394591951900734969518e10, 3.4120417942992754810472370028262e12, 3.5916434929557749619266471215495e14, 3.1096524942448520364797770647969e16, 2.2533721785099826759429898267209e18, }; assert (pow == csc); assert (coeff == csc); assert (coeff == pow); if (value >= Double.MAX_VALUE  value <=Double.MIN_NORMAL){ return 0; }else if(value == 0) { throw new ArithmeticException("division by 0"); }else if(value < 0 ){ throw new IllegalArgumentException("argument must be between 0 and Pi"); }else if(value >Math.PI){ throw new IllegalArgumentException("argument must be between 0 and Pi"); } else{ for(i = 0;i<pow.length;i++){ if(exp<=1){ exp=1; ++exp; factor = (2*exp)+1; }else{ exp = ++l; factor = (2*exp)+1; pow[i] = Math.pow(x, factor); System.out.println(Arrays.toString(pow));//for testing only } } for (j = 0;j<csc.length;j++){ csc[j] = (pow[j] * coeff[j]); System.out.println(Arrays.toString(csc));//used for testing only } for(k = 0;k<csc.length;k++){ sum = sum + csc[k]; System.out.println(Arrays.toString(csc)); } cosecant = term+sum; System.out.printf("%20s \n", "cosecant("+x+")"); System.out.printf("%.16f \n" , cosecant); } return cosecant;
 01172012, 04:18 PM #23Moderator
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Re: Method for calculation Cauchy Inequality with fully implemented handler
Note my argument above is based on the idea that limitSin was a method specifically designed to handle values between a certain range.
Now, if the above cosecant has no such limitation on it then AndreB's use of NaN would be more the standard.
 01172012, 08:16 PM #24Member
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Re: Method for calculation Cauchy Inequality with fully implemented handler
Yes cosecant has similar range constraints , although negative range could be implemented because it is defined mathematically I did not do this and only implemented positive range (0 to Pi).NaN can be returned when division by 0 is encountered(here i think runtime will throw unchecked exception) or input value is out of range.
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