Discussion in 'Electronic Basics' started by Jack Crane, Nov 25, 2004.

1. ### Jack CraneGuest

OK, Robert, you got me. Twice I've entered thru SHIFT SOLVE and the first
prompt is "B?"; and I'm not given a chance to enter A. Does this really
work?

Tried a simpler equation, A-squared = B X C-squared, with A=8, C=2. Same
thing happened.

Jack

2. ### Robert MonsenGuest

Solve uses an iterative solver to try to figure out a numerical
solution. Say you want to figure out the right resistor value to make
divider, but you were too lazy to do the algebra in your head. If your
input voltage was 10 volts, and you wanted 1.7 volts out, you could type

1.7 alpha = 10 * alpha A / ( alpha A + alpha B) shift solve

You then get a prompt for A, as in "A? ". Say you want to solve for A.
Then, hit the down key (the bottom of the circular key). You get a "B?"
prompt. Enter a value for B. (say you have a 10k resistor)

10000 =

then get back to the A? prompt by typing up arrow (the top of the
circular key) and type

shift solve

it'll crank for a bit, then display A= on the first line, and 2.048...k
on the second line. Thus, for a value of B=10k, a value of A=2.05k will
get you 1.7V.

The trick is to use the up and down key to enter values for variables
you have values for, and then use shift solve on the one you want the
value for.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.

3. ### Jack CraneGuest

Did this twice and both times with A= on the first line, the second line
was 0.

Thus, for a value of B=10k, a value of A=2.05k will
Tried a really simple equation, 3 = A*B (3 Alpha = Alpha A * Alpha B),
with B=3. Again, with A= showing on first line, second line showed 0.

Jack

4. ### Robert MonsenGuest

Again, you switch to B using the 'down' key, which is the bottom of the
circular key. Enter the values for the unknowns you want, and then
select the one you want to solve for. enter 'shift solve' and it will
solve the equation if it can do it using iteration.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.

5. ### Jack CraneGuest

Am I wrong to expect the calculator to solve "3=A*B" for A, given B = 3?
I believe I did exactly what you said to do. I'll spell out completely
the keys I pushed : 3, ALPHA, =, ALPHA, A, *, ALPHA, B, SHIFT, SOLVE,
down-arrow, 3, =, up-arrow, SHIFT, SOLVE. At this point the top line
shows A=; the bottom line shows 0. (by * I mean the multiplication key,
"X").

Thanks for being so patient with me.

Jack

6. ### Robert MonsenGuest

No, it works for me.
Make sure you are in 'comp' mode, not 'cmplx' mode. The solve function
does not work in complex mode. Enter 'mode clr' and then '1' to enter
'comp' mode.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.

7. ### Jack CraneGuest

Yes, I've been in comp mode.

Jack

8. ### Robert MonsenGuest

After entering your formula for 3=A*B, can you switch between "A=" and
"B=" on the top display line using up and down arrow?

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.

9. ### Jack CraneGuest

No. After "A=" appears, up-arrow produces "3", and I'm stuck there.
Down-arrow doesn't work after "A=" appears.

Jack

10. ### Robert MonsenGuest

Look at the calculator. There is a big round button right underneath the
center of the display. The up and down buttons are on the top and bottom
of that. Is that what you are pushing? If not, then that's your problem.
If so, then your calculator is broken.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.

11. ### Jack CraneGuest

Yes, that's what I'm pushing.

Thanks,

Jack