# Deep Learning Course notations

Andrew is using symbols like the big R and epsilon without ever explaining what they mean. Did he explain them in an earlier course?
Lecture: https://www.coursera.org/learn/neural-networks-deep-learning/lecture/Z8j0R/binary-classification
Timestamp: 4:40

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Please update you post with a link to the lecture, timestamp and slide.

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āBig Rā is a standard mathematical reference to the space of real numbers. It will also have a superscript that specifies how many dimensions are being considered.

āepsilonā is a common variable used to refer to small changes in some experimental value.

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Hello Tyler,

Welcome to the community and thank you for your question.

You can find all the notations used in DLS course from the following link:

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Ok, I did, thank you

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Ok I guess it isnāt epsilon, itās the one that looks like a fork or like a rounded capital E. You say itās standard, for what kind of math?

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Thank you Rashmi, but that does not help. That page does not define the big R symbol or the rounded E symbol.

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Please post a screen capture image that shows the symbols youāre asking about. I donāt recognize ārounded Eā.

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\in = is in
eg:
If x \in \mathbb{R}, x belongs to the set of real numbers.

1. Basic concepts and notation section here