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Ask iit jee aieee pet cbse icse state board experts Expert Question: signum function
Forum Index -> Differential Calculus like the article? email it to a friend.  
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ruhi (603)

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hi
i ve read in many books about signum function which is represented as sgn(x)=mod(x)/x
now when x>0,the value of function is 1 nd when x<0 the value of function is
 -1.this is quiet easy to understand as when x is >0 means x is positive hence mod(x) is replaced by +x nd we get the value 1 nd when x is <0 x becomes negative nd mod(x) is replaced by -x nd we get -1. but when x=0, in most of the books it is written that the value of function will be 0 in this case. but i want to know that when x=0, the function will be in the form 0/0 which is indeterminate form hence function should not be defined in this case so how come its value is 0???????? plzzzz help me
ruhi
    
ruhi (603)

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nd plz i need an urgent reply
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puneet (3521)

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The books which represent sgn(x) as mod(x)/x have defined it wrong. The actual definition is as follows :
 
                    sgn(x) =  mod(x)/x   when x  0
                            
                              =  0              when x = 0
 
Now the thing should be hopefully clear ......
 
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Puneet Agrawal
IIT Delhi
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