# What is the pronounciation of this letter in english?

#### gholamghar

Hello
My native language is not English an i have a noob! question about the pronounciation of the derivative operator letter in English and how we write its name in English, i have attached the picture of operator.
Thanks

#### Attachments

• 360 bytes Views: 415

#### CompuChip

Homework Helper
It's called "del" or "partial", although in "colloquial" usage people often say "d" when they mean "del".

#### HallsofIvy

Homework Helper
First, it is not a "letter" in the English alphabet. It is a special symbol. I, myself, have never heard it called "del". To me "del" is the vector operator, "nabla", $\nabla$. If f(x, y, z) is a real valued function of x, y, and z (Cartesian coordinates) then "del f" (also called "grad f") is the vector function
$$\nabla f= \frac{\partial f}{\partial x}\vec{i}+ \frac{\partial f}{\partial y}\vec{j}+ \frac{\partial f}{\partial z}\vec{k}$$
Similarly, I have heard "div v" called "del dot v" and "curl v" called "del cross v" for vector function v, though I would not consider any of those as formal as "grad", "div", or "curl".

I have, though, heard $\partial$ called "curly d". The LaTex code for it is "\partial".

Last edited by a moderator:

#### tiny-tim

Homework Helper
Hello gholamghar!

Yes, ∂ isn't an English letter or even a Greek letter like ∑ or π, it's just a symbol.

I believe a lot of people pronounce it "dabba", but I just pronounce it "d" (though I call it "curly d").

(and I also have never heard it pronounced "del", that's for ∇)

#### Redbelly98

Staff Emeritus
Homework Helper
I generally say "partial of f with respect to x", if I want to talk about ∂f/∂x. The symbol "∂" never appears by itself, so I have never worried about what to call it.

#### CompuChip

Homework Helper
I, myself, have never heard it called "del". To me "del" is the vector operator, "nabla", $\nabla$.
Whoops, you are so right.
I meant to say "dau" ([dow]).
* deeply ashamed *

#### Mathitalian

∂ is a letter of Cyrillic alphabet, right? I remember my teacher said it in a lesson.
$$\frac{\partial f}{\partial x}$$
as "de" f over "de" x

Last edited:

#### Pagan Harpoon

Several of my lecturers pronounce it "del." Others use "del" to refer to the gradient operator, as has been mentioned, which can be confusing. Ways I have heard it pronounced from educated people:

Del,
Dau,
D,
Partial.

#### Mark44

Mentor
∂ is a letter of Cyrillic alphabet, right?
Sort of. In Russian, the cursive form of lower case Д is sometimes written as ∂, and sometimes as g. That's always been a little confusing to me. This wike article, http://en.wikipedia.org/wiki/Cyrillic_alphabet, has some good information.
I remember my teacher said it in a lesson.
$$\frac{\partial f}{\partial x}$$
as "de" f over "de" x

#### discrete*

To my knowledge, we say "partial". That's what I've always heard and was told a while ago.

#### Mark44

Mentor
∂ is a letter of Cyrillic alphabet, right? I remember my teacher said it in a lesson.
$$\frac{\partial f}{\partial x}$$
as "de" f over "de" x
If you say "dee" f over "dee" x, someone listening would likely interpret this as the ordinary derivative instead of a partial derivative. There have been a number of times where I was helping someone with calculus over the phone. In such cases you have to be more clear than when you can see the work.
To my knowledge, we say "partial". That's what I've always heard and was told a while ago.
Yeah, me, too. I always pronounce this as "partial of f with respect to x."

#### Mathitalian

If you say "dee" f over "dee" x, someone listening would likely interpret this as the ordinary derivative instead of a partial derivative. There have been a number of times where I was helping someone with calculus over the phone. In such cases you have to be more clear than when you can see the work.
Yes you're right. Here, we use the name of $$\partial$$, that is dɛ in IPA.

#### Nabeshin

Yes, I always just pronounce it 'partial', and have never heard anyone else do differently. This makes sense even when you use shorthand:
$$\partial_x = \frac{\partial}{\partial x}$$

Read as, obviously, partial x. Insert "of" if when operating on something you think it sounds weird to omit it.

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving