Quantcast
Channel: PTC Community : Popular Discussions - Mathcad Usage
Viewing all 1503 articles
Browse latest View live

This variable is undefined error when using Given/Find function, why?

$
0
0

Hi Everyone,

 

I have been using mathcad for some time but it is not until recently i started trying the Given / Find functions.

However, every time i try it, it gives me "This variable is undefined" error right after i enter the Find(...) command and hit the "=" button.

I even tried to follow the quick sheet in the tutorial/help document and it is still happening.

 

Could someone help me out?

 

Greatly apprecitated!

 

 

Alex J


fitting using Linfit

$
0
0
Hello folks, I would be grateful if someone could help me with this general query ...

I have a measurement data set consisting of 186 points, I'm simply fitting a polynomial using the linfit command. The polynomial is:

f(x) := 1 + x + x^2 + x^3 + x^4 .... x^6

The linfit function fits fine if I use just 133 points or less which ever part of the measured data I look at. When I try to fit this equation 134 points or greater it fails.

I'm suspecting that the problem is either to do with how Mathcad goes about fitting or maybe something more fundamental such as the theory of line or curve fitting itself. I know I could try another function but I'm a bit pressed for time to try to find another especially when the one above works so well.

If anyone could shed any light on this I would be grateful. Many thanks in advance!

Cheers, Dinesh

Find() gives solution outside the constraints

$
0
0

Hi all,

 

I have a solve block as follows in MathCAD 15.0:

 

SolveBlockProblem.PNG

 

m=6

Fmin=0.469

Q=0.35

 

I included the constraint line to limit the solution to within the range of 0.469 to 2, but I do not understand why I would get solution which is outside this range, such as 0.345 and the negative numbers.

 

Could someone please help?

 

Thanks!

 

-Alan

Quaternions

$
0
0
To properly understand gradient/divergence/curl you really need to work with quartenions. There are not really three separate and distinct operations, these are all just aspects of a single operator, the quaternion form of del.

The del operator applies to a quaternion field, a quaternion valued function of position in space. The gradient is just the result of applying del to a scalar field (scalars are a subalgebra of quartenions). Divergence is the negative of convergence, and convergence is the scalar part of del applied to a vector field (vectors are a subspace of quaternions). Curl is the vector part of del applied to a vector fiels.

� � � � Tom Gutman

Radian to degrees

$
0
0
I am new to using MathCad, but it seems that I should be able to figure out how to change from radians to degrees. The manual is pretty much worthless, and the help section merely states that MathCad gives results of trig functions in radian mode. No kidding. Any help is appreciated, and yes I feel like a moron.

Solving Equations for undefined variable with units

$
0
0

So, I am confused on how to solve an equation for an unknown with units. I am not sure if I am having unit problems or if my way of stating variables is incorrect. I am simply just trying to solve for the variable "d" which should have units in length. How should I declare variables that rely on other known and unknown variables? When should I solve an equation symbolically and just numerically in terms of getting proper units? I am used to using maple 16 so switching to MathCAD has been fairly intiutive but I am failing to pick up on certain features. If you fix my MathCAD code, I should be able to figure it out from the fix solution. Thanks!

equations.PNG

Mathcad 15 "onefn" function problems

$
0
0

I am having trouble with the onefn function in Mathcad 15.  I get double entries in the 1/f noise vector and if I take the CFFT(ofn) I get a zero as the first result.  Also I do not understand the mirrored magnitude plot of the 1/f Noise.  I also don’t understand why the range variable even starts at zero.  That would give infinity for 1/f.  See attached.

 

Bill

 

Bill Dumke, RF Engineer

Nsight Telservices dba Cellcom

450 Security Blvd

Green Bay, WI 54313

Find() gives solution outside the constraints

$
0
0

Hi all,

 

I have a solve block as follows in MathCAD 15.0:

 

SolveBlockProblem.PNG

 

m=6

Fmin=0.469

Q=0.35

 

I included the constraint line to limit the solution to within the range of 0.469 to 2, but I do not understand why I would get solution which is outside this range, such as 0.345 and the negative numbers.

 

Could someone please help?

 

Thanks!

 

-Alan


Mathcad prime 1.0: bug with keyboard shortcuts with Italian keyboard.

$
0
0

i'm sorry for my bad english

 

I have Mathcad Prime 1.0 on Windows 7 64(bit) Italian.

 

I think that i have found a very fastidious bug.

When i write expression and i use the keyboard shortcuts i have a problem for write exponents.

 

If i use the keyboard and i press ( ^ ) ( ctrl+ì )....mathcad prime don't write for example "x^2" but write "x if ||"

 

It's a very big problem for me because i'm so fast with keyboard shortcuts...and i dont' want to use a mouse command and found always manually the correct operator.

I see that this problem presents only in math form and not in text form.

 

I try to set english keyboard in windows and now Mathcad Prime work correctly both in math form and in text form....

The problem is that i have an Italian keyboard and not an English keyboard.

 

Can You help me??

 

 

Please it's very important i must use Mathcad for some university project!

 

Bye

Radian to degrees

$
0
0
I am new to using MathCad, but it seems that I should be able to figure out how to change from radians to degrees. The manual is pretty much worthless, and the help section merely states that MathCad gives results of trig functions in radian mode. No kidding. Any help is appreciated, and yes I feel like a moron.

Quaternions

$
0
0
To properly understand gradient/divergence/curl you really need to work with quartenions. There are not really three separate and distinct operations, these are all just aspects of a single operator, the quaternion form of del.

The del operator applies to a quaternion field, a quaternion valued function of position in space. The gradient is just the result of applying del to a scalar field (scalars are a subalgebra of quartenions). Divergence is the negative of convergence, and convergence is the scalar part of del applied to a vector field (vectors are a subspace of quaternions). Curl is the vector part of del applied to a vector fiels.

� � � � Tom Gutman

Solving Equations for undefined variable with units

$
0
0

So, I am confused on how to solve an equation for an unknown with units. I am not sure if I am having unit problems or if my way of stating variables is incorrect. I am simply just trying to solve for the variable "d" which should have units in length. How should I declare variables that rely on other known and unknown variables? When should I solve an equation symbolically and just numerically in terms of getting proper units? I am used to using maple 16 so switching to MathCAD has been fairly intiutive but I am failing to pick up on certain features. If you fix my MathCAD code, I should be able to figure it out from the fix solution. Thanks!

equations.PNG

How to find square root of a matrix

$
0
0

How do you find the square of an each individual element of a matrix.

This variable is undefined error when using Given/Find function, why?

$
0
0

Hi Everyone,

 

I have been using mathcad for some time but it is not until recently i started trying the Given / Find functions.

However, every time i try it, it gives me "This variable is undefined" error right after i enter the Find(...) command and hit the "=" button.

I even tried to follow the quick sheet in the tutorial/help document and it is still happening.

 

Could someone help me out?

 

Greatly apprecitated!

 

 

Alex J

fitting using Linfit

$
0
0
Hello folks, I would be grateful if someone could help me with this general query ...

I have a measurement data set consisting of 186 points, I'm simply fitting a polynomial using the linfit command. The polynomial is:

f(x) := 1 + x + x^2 + x^3 + x^4 .... x^6

The linfit function fits fine if I use just 133 points or less which ever part of the measured data I look at. When I try to fit this equation 134 points or greater it fails.

I'm suspecting that the problem is either to do with how Mathcad goes about fitting or maybe something more fundamental such as the theory of line or curve fitting itself. I know I could try another function but I'm a bit pressed for time to try to find another especially when the one above works so well.

If anyone could shed any light on this I would be grateful. Many thanks in advance!

Cheers, Dinesh

Mathcad 15 - Preferred units in results?

$
0
0

I am using Mathcad 15 for a course in Quantum Chemistry. Is there a way to set default units so that they match those commonly accepted in the dicipline?

 

For instance, when I calculate wavenumber, my result is in m^-1 rather than the commonly accepted cm^-1, and frequency is in s^-1 rather than Hz.

 

Thanks.

 

Best Regads,

Matthew

How to find square root of a matrix

$
0
0

How do you find the square of an each individual element of a matrix.

This variable is undefined error when using Given/Find function, why?

$
0
0

Hi Everyone,

 

I have been using mathcad for some time but it is not until recently i started trying the Given / Find functions.

However, every time i try it, it gives me "This variable is undefined" error right after i enter the Find(...) command and hit the "=" button.

I even tried to follow the quick sheet in the tutorial/help document and it is still happening.

 

Could someone help me out?

 

Greatly apprecitated!

 

 

Alex J

fitting using Linfit

$
0
0
Hello folks, I would be grateful if someone could help me with this general query ...

I have a measurement data set consisting of 186 points, I'm simply fitting a polynomial using the linfit command. The polynomial is:

f(x) := 1 + x + x^2 + x^3 + x^4 .... x^6

The linfit function fits fine if I use just 133 points or less which ever part of the measured data I look at. When I try to fit this equation 134 points or greater it fails.

I'm suspecting that the problem is either to do with how Mathcad goes about fitting or maybe something more fundamental such as the theory of line or curve fitting itself. I know I could try another function but I'm a bit pressed for time to try to find another especially when the one above works so well.

If anyone could shed any light on this I would be grateful. Many thanks in advance!

Cheers, Dinesh

Plotting a graph of the function f(x)

$
0
0

Hi all,

 

I am a newbie to the usage of mathcad and could do with some step by step help from you experts out there.

 

I have a mathcad problem:

 

I want to plot a graph of the function f(x) from the equation;

 

f(x) = x(14-7x)(16-7x)

            4(4-x)^2

 

I do not want to show the equation in the worksheet (and so imagine there will be some packets of data on the sheet somewhere that can be referenced to).

 

From the information I need to plot a graph of the function f(x) (repeated myself didn't I).

 

I would like the graph needs to cover the interval [0, 2.68] in the x direction and [0, 80] in the y direction.

 

If anybody can help (step by step because I'm thick....lol). I woul;d be really grateful.

 

Paul

Viewing all 1503 articles
Browse latest View live


<script src="https://jsc.adskeeper.com/r/s/rssing.com.1596347.js" async> </script>