Summarizing a set of expressions on a TI-83 Plus
April 29, 2006 6:44 AM Subscribe
How do I easily summarize a set of expressions on my Texas TI-83 Plus calculator?
Say I want to find the probability of something and I have the expression:
(30 nCr X)*(0.9^X)*0.1^(30-X)
Say X goes from 20 to 30, and I want to sum up all the values given by the expression. What is the quickest way to do this?
Say I want to find the probability of something and I have the expression:
(30 nCr X)*(0.9^X)*0.1^(30-X)
Say X goes from 20 to 30, and I want to sum up all the values given by the expression. What is the quickest way to do this?
0->y
For(x,20,30)
f(x)+y=y
end
print y
or something like it should be the right thing to make a little loop as a calculator program that'll sum up all those f(x)'s.
http://www.ticalc.org/programming/columns/83plus-bas/cherny/
posted by apathy0o0 at 8:21 AM on April 29, 2006
For(x,20,30)
f(x)+y=y
end
print y
or something like it should be the right thing to make a little loop as a calculator program that'll sum up all those f(x)'s.
http://www.ticalc.org/programming/columns/83plus-bas/cherny/
posted by apathy0o0 at 8:21 AM on April 29, 2006
there is a sum function
it looks like a sideways M
iirc, the syntax is:
Sum(expr, var, lower, upper)
posted by lpctstr; at 11:49 AM on April 29, 2006
it looks like a sideways M
iirc, the syntax is:
Sum(expr, var, lower, upper)
posted by lpctstr; at 11:49 AM on April 29, 2006
Best answer: I've been using my TI-83 (original) for years, ever since I bought it for high school math. I'm always amazed at how good it is with complex expressions, assuming you're familiar with its features.
I'm not sure if X is supposed to be an integer, but if that's the case, the expression would be:
posted by zixyer at 2:15 PM on April 29, 2006
I'm not sure if X is supposed to be an integer, but if that's the case, the expression would be:
sum(seq((30 nCr X)*(0.9^X)*0.1^(30-X),X,20,30,1))"sum" is located in the math submenu of the list button and seq is located in the ops submenu of same.
posted by zixyer at 2:15 PM on April 29, 2006
Best answer: Oh yeah, and in case you can't figure it out from the example, the syntax of "seq" is seq(exp, var, first, last, delta) which generates a list, each element determined by evaluating exp with var set from first to last incremented by delta. "sum" just gives you the sum of all the elements in a list.
posted by zixyer at 2:27 PM on April 29, 2006
posted by zixyer at 2:27 PM on April 29, 2006
when i need to do things like this i usually enter the expression in the graphing feature. Then look at the table feature to get the values. You can go to 'tableset' and give it a range of values to work with.
posted by I_am_jesus at 6:20 PM on April 29, 2006
posted by I_am_jesus at 6:20 PM on April 29, 2006
Response by poster: zixyer, you got it! Great.
lpctstr;, I think that's actually how it's done on the casio calcs. That's actually why I wanted to know this, that I saw someone do that with their casio.
So yes, thank you my all, I'll now be mister super efficient on my math exam. Woot and yay!
posted by cheerleaders_to_your_funeral at 1:46 AM on April 30, 2006
lpctstr;, I think that's actually how it's done on the casio calcs. That's actually why I wanted to know this, that I saw someone do that with their casio.
So yes, thank you my all, I'll now be mister super efficient on my math exam. Woot and yay!
posted by cheerleaders_to_your_funeral at 1:46 AM on April 30, 2006
cheerleaders_to_your_funeral: I think you're right. I may be thinking of the ti89
posted by lpctstr; at 1:53 PM on April 30, 2006
posted by lpctstr; at 1:53 PM on April 30, 2006
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posted by ludwig_van at 7:33 AM on April 29, 2006