## Solving equation problem

## Solving equation problem

(OP)

Hi. I would like to calculate an equation with variables in range of values (in Given - Find block), but I have problem with that. Let me explain on example what I'm talking about. I write:

y=1..4 (range of values for variable y)

Given

x(y)=1 (initial guess)

x(y)=2*x(y)+1 (logical equation)

r(y)=Find(x(y))

When i type "r(y)=" Mathcad report a problem: "initial guess must consist of numbers and matrices". I don't know how exactly i should change the initial guess. Any idea ? Thanks for help.

y=1..4 (range of values for variable y)

Given

x(y)=1 (initial guess)

x(y)=2*x(y)+1 (logical equation)

r(y)=Find(x(y))

When i type "r(y)=" Mathcad report a problem: "initial guess must consist of numbers and matrices". I don't know how exactly i should change the initial guess. Any idea ? Thanks for help.

## RE: Solving equation problem

Steve

## RE: Solving equation problem

## RE: Solving equation problem

Back to your problem though, could the issue be that your guess value is apparently a function x(y)=1.

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## RE: Solving equation problem

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## RE: Solving equation problem

blah = 2*blah+1 blah = -1 always

TTFN

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## RE: Solving equation problem

y=1..4 (range of values for variable y)

Given

x=1 (initial guess)

y(x)=2*x(y)+1 (logical equation)

r(y)=Find(x(y))

How about that ?

## RE: Solving equation problem

y=1..4 (range of values for variable y)

Given

x=1 (initial guess)

y=2*x(y)+1 (logical equation)

r(y)=Find(x(y))

Somebody know what is wrong with this ?

## RE: Solving equation problem

> You cannot place an undefined function on the right hand side of ANY definition or constraint

> In your specific example x(y) should simply be x

> However, our construct has a closed form solution of the apparent function inversion that you appear to be looking for, so a given-find is a rather tedious way of finding the answer, and will not give you the functional relationship, in any case:

x = (y-1)/2

This is the type of problem that you could the symbolic functionality of Mathcad, as opposed to the numerical functionality.

TTFN

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## RE: Solving equation problem

## RE: Solving equation problem

Given

y:=1 (initial guess - y)

x:=1 (initial guess - x)

y=2*x+1 (logical equation) (relation)

r(y)=Find(x)

then

y:=1..4 (range of values for variable y)

r(y)=

## RE: Solving equation problem

What does x have to do with this?

Peter Nachtwey

Delta Computer Systems

http://www.deltamotion.com

## RE: Solving equation problem

r(y) = y/2 - 1/2

See Quicksheets Solving Equations, Symbolic Solutions of Equations.

## RE: Solving equation problem

Regards

Mike