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# Solving stored complex equations on the HP50g

05-10-2013 12:58 AM

Hello,

I have stored the 2 equations **Δ **&** K**, but when I try to solve them in the** num. solv. **I get the message** bad guess(es). **I searched on google and it seems that is because I'm working with** complex numbers **and the** num. solv. **can't handle them. However, I haven't found the right way to solve them. I have to use the two equations a lot, so it would be great if you could help me finding a solution where I can solve them entering the values of the variables, just like with the** num. solv.**

Solved! Go to Solution.

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## Solving stored complex equations on the HP50g

05-11-2013 08:38 AM

it is __not__ clear what problem you are trying to solve....

on the surface, it looks like you have provide 2 equations with 4 unknowns... S11, S22, S21, S12

OR are you saying that you first want the values shown in the post:

S11=0.45∠-54.5

S22=0.79∠-21.5

__substituted first__ into the equations

and then the equations solved for the unknowns S21 & S12 ?

you can also reference the following videos... just skip past the engineering part to the point where the equations are being made and entered into the 50G... it __might__ help....

However, the entry method is shown in RPN format... are you still using Algebraic mode?

this video demonstrates solving equations for unknowns

http://www.youtube.com/watch?v=vj9K_bXKEY4

this video demonstrates arithmetic with complex numbers

http://www.youtube.com/watch?v=dAUMdDaIq_s

OR

are you trying to find a method to substitute values for all the unknowns and then solve for Delta and K?

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## Solving stored complex equations on the HP50g

05-11-2013 09:30 AM

Thanks for your answer. I have to use both equations in several exercises, so I stored the equations in order to save time, so whenever I have to use them, I don't have to write them down, I just have to type the values of the unknowns.

Example:

__First exercise:__

*S11=0.45∠-54.5*

*S22=0.79∠-21.5*

*S12=0.5∠-5.5*

*S21=0.7∠-1.5*

I go to the** num. solv.** I choose the equation I type the values and I obtain the results.

__Second exercise:__

__ __

*S11=5∠90*

*S22=1.9∠46.3*

*S12=2.5∠-55.6*

*S21=1.7∠-59.5*

I go to the** num. solv.** I choose the equation I type the values and I obtain the results.

and so on...

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## Solving stored complex equations on the HP50g

05-11-2013 09:57 AM

are you using Algebraic mode or RPN?

here is how you can generally enter the complex values like you showed...

I'm guessing for now Algebraic mode; however this general process works for BOTH Algebraic or RPN:

make sure you have the __correct angle mode selected__... degrees, radians...

LEFT SHIFT minus key @this will put parenthesis on the stack

.45

SPACE key

ALPHA

RIGHT SHIFT

6 key @this will insert the "∠" symbol

54.5 CHS @where CHS is the +/- key

ENTER

this method will work in BOTH the main display and when entering values in NUM.SLV "solve equation"

HOWEVER, in "solve equation" the cursor must have the equation to solve highlighted...

then press F6 (expr=) this will put the __solution on the stack__. not in the display

so to temporarily "escape" from the "solve equation" screen do the following

press the NXT key

the softkey F2 is now labeled CALC

press CALC

this will "escape" to the 50G screen and you can see the result

now press CANCEL (F5) (or the ON key) and you return to the "solve equation" screen

press NXT and the softkeys are availabe to change equation/variables

there are other methods that can be used... once you state whether you are using Algebraic or RPN entry mode, these can be shown.

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## Solving stored complex equations on the HP50g

05-11-2013 10:54 AM

Thank you, it worked. I'm using **algebraic**, so if you could give me some other ways it would be great.

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## Solving stored complex equations on the HP50g

05-11-2013 11:10 AM

FYI, make sure you go back and read your old post... the method to enter equations with existing values using EQW is demonstrated in the last entry and was unfortunately __added after__ you received the answer to your question...

here's the easiest method

with all four variables stored... S11, S22, S21, S12

press the following keys...

EVAL

softkey for DELTA

ENTER

EVAL

softkey for K

ENTER

there is another method using MENU (30)

however, I'm going to have to work out the process as I am not as familiar with Algebraic entry mode....

unless some other forum member knows how to use MENU (30) __in Algebraic mode__ and can post post the process,

will try and post the process later this evening....

MENU 30 is generally described starting on page 6-26 of the 50G Users Guide (not users manual)

the section is title "SOLVR sub-menu"

the manual describes the process as

MENU(74)

ENTER

press F1 (root)

press F1 (solvr)

MENU(30)

ENTER

is the direct access

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## Solving stored complex equations on the HP50g

05-11-2013 06:36 PM

MENU 30 is generally described starting on page 6-26 of the 50G Users Guide (not users manual)

the section is title "SOLVR sub-menu"

the manual describes the process as

MENU(74)

ENTER

press F1 (root)

press F1 (solvr)

OR for direct access execute:

MENU(30)

ENTER

with the equations for Delta and K saved

no variables are currently stored (all old variables deleted)

put one of the equations on the stack

for this example, 'K' will be put on the stack

K (softkey)

ENTER

now execute

STO> 'EQ'

execute

MENU(30) @make sure the parenthesis are around the number 30

ENTER

this will begin the solver for the equation currently stored in the variable EQ... which is now 'K'

the screen should look like this:

follow the previously defined procedure to create a complex variable and put that variable on the stack

for this example, the value for S11 will be entered on the stack

(0.45 ∠-54.5)

execute

STO> S11 (to create the "S11" for the store function, press the softkey for S11, you don't have to type "S11")

ENTER

(0.79∠-21.5)

STO> S22 (to create the "S22" for the store function, press the softkey for S22, you don't have to type "S22")

ENTER

(0.5∠-5.5)

STO> S12 (to create the "S12" for the store function, press the softkey for S12, you don't have to type "S12")

ENTER

(0.7∠-1.5)

STO> S21 (to create the "S21" for the store function, press the softkey for S21, you don't have to type "S21")

ENTER

to recall one of the variables, just press the softkey for the variable and press ENTER.. the variable value will be put on the stack

to solve the equation press the EXPR= softkey

the screen will look like the following:

to change the equation

press VAR

press the softkey for DELTA

press ENTER

execute

STO>'EQ'

execute

MENU(30)

ENTER

press EXPR= softkey

the screen will look like the following:

after you gain some experience and learn how to program the 50G, you can also build a very simple program using the INFORM command.... similar to what is shown in the following forum post

/t5/Calculators/Using-a-matrix-with-variables-in-it/m-p/5952515#M12675

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## Solving stored complex equations on the HP50g

05-11-2013 09:08 PM

Hi!, JamesJames:

For your help in HP50G, you can see __ compmara.zip__, of Nick Karagiaouroglou ... http://www.hpcalc.org/details.php?id=5114

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## Solving stored complex equations on the HP50g

05-11-2013 10:26 PM

there is one additional feature of the "SOLVR sub-menu".. (menu 30)

if there are multiple equation to solve, as in your example, the equations can be put into a list.

the list of equations can be stored in the variable EQ.

when MENU(30) is executed, an additional softkey will be available to select the equation to solve with softkey EXPR=

to create the list of equation __in algebraic mode__, do the following

LEFT SHIFT

+ @puts curly brackets on stack

RIGHT ARROW @ this moves the cursor to the right side of the curly braces

+

K softkey

+

DELTA softkey @ as many equations as needed can be added to the list

your screen will look like the following

press ENTER

the screen will look like the following

both equations are now in a list..

now store the list to the variable EQ

STO>'EQ'

start the SOLVE sub-menu

MENU(30)

the screen will now show the current equation to be solved at the TOP of the display

notice that softkey F6 now has the function NXEQ

press F5 (expr=) and the display shows:

press F6 and the equation to be solved (shown at the top of the screen) when F5 is pressed changes.

press F5 (expr=) and the display shows:

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## Solving stored complex equations on the HP50g

05-12-2013 06:43 AM

Hi!, JamesJames:

For your exercises, you can see the results ...

__ First__:

S11=0.45∠-54.5

S22=0.79∠-21.5

S12=0.5∠-5.5

S21=0.7∠-1.5

* *and result ...

__ Second__:

S11=5∠90

S22=1.9∠46.3

S12=2.5∠-55.6

S21=1.7∠-59.5

and result ...