Math.Round Question

[Gonza]

Hi group, i have a method in my class with the following code:

private double GetCompletedPer centage(TimeSpa n totalTime, TimeSpan
budgetedTime)
{
double totalMinutes = totalTime.Total Minutes;
double budgetedMinutes = budgetedTime.To talMinutes;

return Math.Round((tot alMinutes * 100) / budgetedMinutes ,2);
}

Sometimes, budgetedMinutes is zero, but the result of the operation in
infinite?? why is that?? Can I check against a constant or something to
see if it's infinite?? I know, i can check if budgetedMinutes == then
return something, but i'm curious.

Thanks in advance

[Thomas T. Veldhouse]

Re: Math.Round Question

Gonza <gonzalow@gmail .comwrote:

Hi group, i have a method in my class with the following code:
>
private double GetCompletedPer centage(TimeSpa n totalTime, TimeSpan
budgetedTime)
{
double totalMinutes = totalTime.Total Minutes;
double budgetedMinutes = budgetedTime.To talMinutes;
>
return Math.Round((tot alMinutes * 100) / budgetedMinutes ,2);
}
>
Sometimes, budgetedMinutes is zero, but the result of the operation in
infinite?? why is that?? Can I check against a constant or something to
see if it's infinite?? I know, i can check if budgetedMinutes == then
return something, but i'm curious.

Anytime you divide any number by zero you get infinity. Simple math.

--
Thomas T. Veldhouse
Key Fingerprint: 2DB9 813F F510 82C2 E1AE 34D0 D69D 1EDC D5EC AED1

[Christof Nordiek]

Re: Math.Round Question

Hi,

you can check the IsInfinity property:

double result = Math.Round(.... );
if (result.IsInfin ity)
....
else
....


"Gonza" <gonzalow@gmail .comschrieb im Newsbeitrag
news:1160571400 .545653.282660@ c28g2000cwb.goo glegroups.com.. .

Hi group, i have a method in my class with the following code:
>
private double GetCompletedPer centage(TimeSpa n totalTime, TimeSpan
budgetedTime)
{
double totalMinutes = totalTime.Total Minutes;
double budgetedMinutes = budgetedTime.To talMinutes;
>
return Math.Round((tot alMinutes * 100) / budgetedMinutes ,2);
}
>
Sometimes, budgetedMinutes is zero, but the result of the operation in
infinite?? why is that?? Can I check against a constant or something to
see if it's infinite?? I know, i can check if budgetedMinutes == then
return something, but i'm curious.
>
Thanks in advance
>

[Michael C]

Re: Math.Round Question

"Gonza" <gonzalow@gmail .comwrote in message
news:1160571400 .545653.282660@ c28g2000cwb.goo glegroups.com.. .

Sometimes, budgetedMinutes is zero, but the result of the operation in
infinite?? why is that??

How many free burgers can you eat for a dollar? :-)

Can I check against a constant or something to
see if it's infinite?? I know, i can check if budgetedMinutes == then
return something, but i'm curious.

You can use checks like this but you are much better off checking if the
divisor is zero.

double x = 1.0 / 0.0;
bool a1 = double.IsNaN(x) ;
bool b1 = double.IsInfini ty(x);
bool c1 = double.IsNegati veInfinity(x);
bool d1 = double.IsPositi veInfinity(x);
bool e1 = (x == double.Negative Infinity);
bool f1 = (x == double.Positive Infinity);
bool g1 = (x == double.NaN);

x = -1.0 / 0.0;
bool a2 = double.IsNaN(x) ;
bool b2 = double.IsInfini ty(x);
bool c2 = double.IsNegati veInfinity(x);
bool d2 = double.IsPositi veInfinity(x);
bool e2 = (x == double.NaN);
bool f2 = (x == double.Negative Infinity);
bool g2 = (x == double.Positive Infinity);

Michael

[Christof Nordiek]

Re: Math.Round Question

Or better:

if (budgetMinute2 == 0)
....
else
return Math.Round(...) ;


"Christof Nordiek" <cn@nospam.desc hrieb im Newsbeitrag
news:eY7pJhT7GH A.1256@TK2MSFTN GP04.phx.gbl...

Hi,
>
you can check the IsInfinity property:
>
double result = Math.Round(.... );
if (result.IsInfin ity)
....
else
....
>
>
"Gonza" <gonzalow@gmail .comschrieb im Newsbeitrag
news:1160571400 .545653.282660@ c28g2000cwb.goo glegroups.com.. .

>Hi group, i have a method in my class with the following code:
>>
>private double GetCompletedPer centage(TimeSpa n totalTime, TimeSpan
>budgetedTime )
>{
> double totalMinutes = totalTime.Total Minutes;
> double budgetedMinutes = budgetedTime.To talMinutes;
>>
> return Math.Round((tot alMinutes * 100) / budgetedMinutes ,2);
>}
>>
>Sometimes, budgetedMinutes is zero, but the result of the operation in
>infinite?? why is that?? Can I check against a constant or something to
>see if it's infinite?? I know, i can check if budgetedMinutes == then
>return something, but i'm curious.
>>
>Thanks in advance
>>

>
>

[Michael C]

Re: Math.Round Question

"Christof Nordiek" <cn@nospam.dewr ote in message
news:eY7pJhT7GH A.1256@TK2MSFTN GP04.phx.gbl...

Hi,
>
you can check the IsInfinity property:
>
double result = Math.Round(.... );
if (result.IsInfin ity)

IsInfinity is static.

Michael

[Michael C]

Re: Math.Round Question

"Gonza" <gonzalow@gmail .comwrote in message
news:1160571400 .545653.282660@ c28g2000cwb.goo glegroups.com.. .

Coooool :-) I've just realised I can simplify some existing code. I've got
some code like this to get the angle of a rise over a run:

if(run == 0)
{
return (rise < 0 ? 90 : -90)
}
else
{
return Atan(rise / run) * 180 / pi;
}


because double can have values of -infinity or +infinity I can simplify the
code to

Atan(rise/run);

Thanks for the tip!! Reading these groups it seams I learn something new
every day :-)

Are there any other similar things I'm missing?

Michael

[Christof Nordiek]

Re: Math.Round Question

Hi Michael,

you also could use

Atan2(rise, run)

(though it would give different result for negative run).

"Michael C" <nospam@nospam. comschrieb im Newsbeitrag
news:OnKq1Jb7GH A.1244@TK2MSFTN GP03.phx.gbl...

"Gonza" <gonzalow@gmail .comwrote in message
news:1160571400 .545653.282660@ c28g2000cwb.goo glegroups.com.. .
>
Coooool :-) I've just realised I can simplify some existing code. I've got
some code like this to get the angle of a rise over a run:
>
if(run == 0)
{
return (rise < 0 ? 90 : -90)
}
else
{
return Atan(rise / run) * 180 / pi;
}
>
>
because double can have values of -infinity or +infinity I can simplify
the code to
>
Atan(rise/run);
>
Thanks for the tip!! Reading these groups it seams I learn something new
every day :-)
>
Are there any other similar things I'm missing?
>
Michael
>

[Michael C]

Re: Math.Round Question

"Christof Nordiek" <cn@nospam.dewr ote in message
news:OylISjc7GH A.3280@TK2MSFTN GP02.phx.gbl...

Hi Michael,
>
you also could use
>
Atan2(rise, run)

Cool, that's exactly what I need.

(though it would give different result for negative run).

That simplifies things though. Before I had 2 different checks to see what
quadrant the result was in, now I only need to add 2pi if the result is less
than zero. Thanks for the tip.

I also noticed
Math.DivRem;
Math.IEEERemain der;
Math.BigMul;

Not sure how useful BigMul is but the other 2 could be useful, saves doing a
mod and a divide in some cases.

Michael