Calculation not working properly

[=?Utf-8?B?ZG9uZGlnaXRlY2g=?=]

I having problems getting this function to return the correct value.
Basically I have a curveDataCalc method that loops as it should, but just
doesn't seem to be working right. I've stepped through the function and the
variables are being passed through correctly its just the clocksPerQREV and
calcAngleTime are never being calculated and are always zero. This causes the
other values to incorrectly calculated, ultimated giving me the wrong
advanceAngle values. Maybe I am missing a conditional statement, but I can't
seem to figure it out right now. Any suggestions would be helpful.


// CALCULATE ADVANCE ANGLE USING curveDataCalc METHOD
double[] advAngle = new double[64];
for (int p = 0; p < 64; p++)
{
advAngle[p] = curveDataCalc(r pmArray[p], multiplier[p],
offset[p]);
}
}
#endregion


public double curveDataCalc(i nt rpmArray, int multiplier, int offset)
{
//CONSTANTS
int calcAngle = 90;
int leadAngle = 72;
double clockPeriod = 0.000004; //timer clock
period = 4uS
int clocksPerMin = 15000000; //# of clock cycles
per minute

//CALCULATED VALUES
double clocksPerQREV = clocksPerMin*(c alcAngle/360);
double calcAngleTime = (clocksPerQREV/(rpmArray*100)) ;
double delayTime = ((calcAngleTime *multiplier)/256) - offset;
double delayAngle = 6*(delayTime*cl ockPeriod*(rpmA rray*100));
double advanceAngle = leadAngle - delayAngle;
return advanceAngle;
}

[Arnie]

Re: Calculation not working properly

//CONSTANTS

int calcAngle = 90;
//CALCULATED VALUES
double clocksPerQREV = clocksPerMin*(c alcAngle/360);

Well, for a start, calcAngle which is 90, divided by 360 in integer
division, will always be zero

- Arnie

[Peter Duniho]

Re: Calculation not working properly

On Tue, 21 Oct 2008 10:28:01 -0700, dondigitech
<dondigitech@di scussions.micro soft.comwrote:

I having problems getting this function to return the correct value.
Basically I have a curveDataCalc method that loops as it should, but just
doesn't seem to be working right. I've stepped through the function and
the
variables are being passed through correctly its just the clocksPerQREV
and
calcAngleTime are never being calculated and are always zero. [...]

Try changing "calcAngle/360" to "calcAngle/360.0". Make sure you don't
have any other similar examples of an integer division where you really
wanted a floating point division (if you find any, fix them so that they
do floating point division by making sure at least one operand is floating
point).

[Ben Voigt [C++ MVP]]

Re: Calculation not working properly

Arnie wrote:

> //CONSTANTS
> int calcAngle = 90;
> //CALCULATED VALUES
> double clocksPerQREV = clocksPerMin*(c alcAngle/360);

>
Well, for a start, calcAngle which is 90, divided by 360 in integer
division, will always be zero

So take out the parentheses if you want to round to integer, or use 360.0 if
you want fractional results.

>
- Arnie

[=?Utf-8?B?QXJ0aHVyIFBhcmtlcg==?=]

RE: Calculation not working properly



"dondigitec h" wrote:

I having problems getting this function to return the correct value.
Basically I have a curveDataCalc method that loops as it should, but just
doesn't seem to be working right. I've stepped through the function and the
variables are being passed through correctly its just the clocksPerQREV and
calcAngleTime are never being calculated and are always zero. This causes the
other values to incorrectly calculated, ultimated giving me the wrong
advanceAngle values. <snip>

Just make all the variables involved in the calculation double, instead of
int.

[MC]

Re: Calculation not working properly

I think what's getting you is that when you put the operator / between two integers, it does integer division; thus (to take a simple example) 3/4 comes out 0 rather than 0.75. For floating-point division, at least one of the arguments needs to be a floating-point type.