if function

[wkhalid]

Hi

How can I use if function when I have two statement shall be valid at the same time:

For example:

y=0 if x=5 and z=10

y=1 otherwise

How can I replace "and"?

Thanks

[MikeArmstrong · Accepted solution]

Like so.

[MikeArmstrong]

Sorry, the and function can be found on the Boolean toolbar or by Ctrl+&.

[ValeryOchkov]

if function not operator:

y:=if(x=5 ^ z=10, 0, 1)

or

y:=if(x=5, if((z=10, 0,), 1)

[MikeArmstrong]

Of course Valery. There is more thanone way to skin a cat

[ValeryOchkov]

Mike Armstrong wrote:

Of course Valery. There is more thanone way to skin a cat

But only one is correct

Do you know differents:

y:=if(x=5 ^ z=10, 0, 1)

y:=if(x=5, if((z=10, 0, 1), 1)

y:=if(z=10 ^ x=5, 0, 1)

y:=if(z=10, if((x=5, 0, 1), 1)

[MikeArmstrong]

You sure!!!!

[ValeryOchkov]

If x not equal 5 we do not need to check z=10: if..(if.. is more correct than ... and ...

[Werner_E]

Valery Ochkov wrote:

If x not equal 5 we do not need to check z=10: if..(if.. is more correct than ... and ...

Its sure equally correct but it may be a bit more efficient.

[ValeryOchkov]

Werner Exinger wrote:

Valery Ochkov wrote:

If x not equal 5 we do not need to check z=10: if..(if.. is more correct than ... and ...

Its sure equally correct but it may be a bit more efficient.

Why I point it!?

Two days ego I have corrected one function in WaterSteamPro set - I have replaced the end operator on two if/ Now we have no error in it!

[Werner_E]

Why I point it!?

Two days ego I have corrected one function in WaterSteamPro set - I have replaced the end operator on two if/ Now we have no error in it!

Not sure what you mean by "replace end operator".

When evaluating a combined boolean expression, Mathcad uses shortcut evaluation - sometimes also calles short-circuit evaluation. That means if we have ... A AND B .... and A is already false, B is not evaluated at all. This is very often convenient but its dangerous because as far as I know its not documented so PTC may change that behaviour without notice. So the order of the operands in a logical combined expression matters and you are on the safe side, if you use nested if's. Not considering this may have been the casuse for the error in your sheet.