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Help with Cas program
01-03-2014, 08:48 PM
Post: #1
Help with Cas program
Hi, I wonder if someone could please help.
After reading many posts about using Cas commands/functions in Home view, I think I am now totally confused AND frustrated.
I have written a program which requests the user to input a function and this is then stored in F1. I then use a loop to generate a table of values based on a start and end value (interval) using a step increment. I store these values in list, say L1.
This works well for any non Cas function, eg e^X, Sin(X), X^2 etc.

The problems start when a Cas function is entered, for example int(Sin(X^2),X,0,X).
I have tried various suggestions in my program to correctly evaluate this function eg:

1. L1(1):=Cas('F1(.1)')

2. L1(1):=Cas("F1(.1)")

3. L1(1):=Eval(Cas('F1(.1)') etc,etc.

I either get some value*X, or incorrect values or just plain 0.

I hope I have explained the problem in an understandable manner.
Thanks for any advice.
John
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01-03-2014, 09:14 PM (This post was last modified: 01-03-2014 09:40 PM by Michael de Estrada.)
Post: #2
RE: Help with Cas program
Replace X with x for your function variable. Also, do not make your upper limit of integration the same as your function variable. It should be your input value. For example: int(SIN(x^2),x,0,X) will work. Make sure you have complex checked in your CAS settings, since SIN is converted to its complex exponential form. If you use it in a program, use the form CAS("L1(1):=int(SIN(x^2),x,0,X) ").
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01-03-2014, 09:47 PM
Post: #3
RE: Help with Cas program
Try the above suggestions by Michael. If that doesn't help, post your code, that will make it easier to ferret out any problems.
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01-07-2014, 07:32 PM
Post: #4
RE: Help with Cas program
Hi Michael and Helge, apologies for not replying earlier to your advice.

In the end, I used the integral template enclosed in single quotes and used a variable other than X for the upper limit.
A simple L1(var):=Eval(F1); worked!!
No use of Cas. or Cas("L1():=..."). Really confusing at times.

By the way Michael, if I used lower case x in defining the function in Home view,as suggested, results in an error.
Thanks to both of you for the suggestions.
Regards
John
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01-07-2014, 11:10 PM
Post: #5
RE: Help with Cas program
Glad that worked out for you!
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