what is the elegant way to make EJS measure a true period of an oscillation?

[lookang]

what is the elegant way to make EJS measure a true period of an oscillation?

I want to make a pendulum to measure the true period.

i tried

if ( omega < 0.001 & omega > -0.001 ) {  // my inital idea how to detect the end points of the oscillation
  count = count+1;  // make count increase by 1 if condition met
}


if (  count ==2 ) {  // count =2
  T1 = t ;  // T1 = t
}

it doesn't work.

any tips work to do it?

[Fu-Kwun Hwang]

1. The AND operator operator you want is && not &.
 & is bitwise AND

2.

Code:

if ( omega < 0.001 && omega > -0.001 ) 

is not a good condition
What if acceleration is very small, omega still smaller then 0.001 in two or more time step.
And if the pendulum starts with omega=0, you might get half period only.

What about define a omegas to store previous omega and change the condition to

Code:

if( omega*omegas<0){
 count=count+1;
}
omegas=omega;/save old value
if(count==2){
 T=t-ts;// period=time differences, not necessary starts from t=0
 ts=t;
 count=0;//you need to reset the counter, unless you only want to calculate the first period
}

However, the above code work only if the pendulum starts with omega=0;

[lookang]

indeed an elegant/clever way to find true period.

thanks!

will try to implement into my pendulum asap

if( omega*omegas<0){
 count=count+1;
}
omegas=omega;//save old value
if(count==2){
 T=t-ts;// period=time differences, not necessary starts from t=0
 ts=t;
 count=0;//you need to reset the counter, unless you only want to calculate the first period
}

will update my progress on your forum soon