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"Algebraic" IF Statement Evaluation

I need to evaluate...

IF(t,1,0) (If t is true, output 1, if t is false, output 0 (numeric), t may be something like V11 >= 7, for example)

BUT I have no IF statement handling capability at this level of a simulation.

I do have algebraic capability.

Is there some cute way to do this algebraically?

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

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| 1962 |

"When the government fears the People, that is Liberty. When the People fear the Government, that is Tyranny." - attributed to Thomas Jefferson by his contemporaries

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Reply to
Jim Thompson
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X=int(V11/7) X/X

Reply to
qrus19

gah! messed that up :S

Reply to
qrus19

For your example, V11>=3D7:

(abs(V11-7))/(V11-7) will be +1 for V11>7, -1 for V11

Reply to
Tim Shoppa

t=X/X

This will sorta work, but if x is 0 then you'll probably get errors, to a human it's the 0/0 = 1 thing not having used your emulator I can't be sure what'll happen of how to treat an error like this.

Reply to
qrus19

I don't have INT available, I do have ABS and some trig functions

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
 Stormy on the East Coast today... due to Bush\'s failed policies.
Reply to
Jim Thompson

That's what I came up with, except I inserted a small "delta" (smaller than my step size) to avoid 0/0. I was hoping for something more compact :-(

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
 Stormy on the East Coast today... due to Bush\'s failed policies.
Reply to
Jim Thompson

Do you have a unit step function (u(x)) available?

--
Paul Hovnanian  paul@hovnanian.com
----------------------------------------------------------------------
Have gnu, will travel.
Reply to
Paul Hovnanian P.E.

I don't have function SGN :-(

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
 Stormy on the East Coast today... due to Bush\'s failed policies.
Reply to
Jim Thompson

(1+sgn(V11-7))/2 ?

Reply to
Spehro Pefhany

y = V11 -7

(abs(y) + y)/(2*y)

Reply to
Spehro Pefhany

P.S. If you want avoid awkward situations very near y == 0 you could do

(abs(y) + y)/(2* abs(y) + e)

where e is a very small positive number

Reply to
Spehro Pefhany

are there any operators or functions that can give a different mumeric result depending on the truth of the input.

many systems have false as 0 and true as 1 (or less common -1)

else maybe something like (sgn( sgn(V11-7) *2 +1 ) + 1 ) /2

Reply to
Jasen Betts

ABS has an intrinsic "if" that can do it. Spehro showed the method.

Reply to
Tom Del Rosso

Use PostScript for your simulation, of course.

with t on stack, {1}{0} ifelse

formatting link 

--
Many thanks,

Don Lancaster                          voice phone: (928)428-4073
Synergetics   3860 West First Street   Box 809 Thatcher, AZ 85552
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Reply to
Don Lancaster

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