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How to implement and if statement in the calculator

LuisGutierrez

Hi all,

I am simulating a pre-regulator with an overvoltage reset and a deglitch filter. I use the function cross to determine when the output voltage crosses the reset value (both rising t1 and falling t2) and use this times to determine the violation time. 

t1 = cross(VT("/vout") 8.6 1 "rising" nil nil)

t2 = cross(VT("/vout") 8.6 1 "falling" nil nil)

However, in some of my corner simulations either the rising/falling edge or both is not triggered by the cross function and it evaluates to nil, giving me an evaluation error later on. I wonder if there is a way to implement and if statement that determines that whether t1,2 equals "nil" and then overrides their value to some numerical value that I can use later on.

I suppose that is done via the calculator special functions using calCreateSpecialFunction and calRegisterSpecialFunction. However, the usage of these functions is not quite clear in the manual. Any input/example on how to do this is much appreciated.

Regards,

Lucho.

  • Hi all,

    I managed to solve the issue by implementing the if statements within the expression as follows:

    if(cross(VT("/vout") 8.6 1 "rising" nil nil) == nil then t1=1 else t1=cross(VT("/vout") 8.6 1 "rising" nil nil))

    With this, if the expression evaluates to nil I assign my desired value there. If it passes normally, I get the result of the cross calculation. This ain't the most elegant way but for now it does the trick. I'm still interested in how to implement this in a custom function. I can't seem to be pass the arguments to the function properly; i.e. how to run the if with a value coming from the stack ?

    Bonus track: How to delete previously loaded functions via calRegisterSpecialFunction?

    Best regards,

    Lucho.

  • Unknown said:

    Bonus track: How to delete previously loaded functions via calRegisterSpecialFunction?

    Lucho,

    I don't believe there is a way of doing this. However, since quitting virtuoso and re-starting will remove the registered functions anyway (unless  you're calling calRegisterSpecialFunction in the .cdsinit), there's not really a big need for an unregister function...

    Regards,

    Andrew.

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