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# Date Archive: 2011 May

Products

## Mathematica Q&A: Three Functions for Computing Derivatives

Got questions about Mathematica? The Wolfram Blog has answers! We'll regularly answer selected questions from users around the web. You can submit your question directly to the Q&A Team using this form. This week's question comes from Bashir, a student: What are the different functions for computing derivatives in Mathematica? The main function for computing derivatives in Mathematica is D, which computes the familiar partial derivative of an expression with respect to a variable: D supports generalizations including multiple derivatives and derivatives with respect to multiple variables, such as differentiating twice with respect to x, then once with respect to y: And vector and tensor derivatives, such as the gradient:

## Former Microsoft CTO Uses Mathematica to Explore the Science of Modernist Cuisine

Ever wondered how to grill the perfect steak? Or how well dunking food into an ice bath stops the cooking process? Nathan Myhrvold used Mathematica to answer these questions, and many others. Myhrvold, the first chief technology officer at Microsoft, has had a longtime interest in cooking and has a background in science and technology. When he started using new techniques like sous vide, in which food is slowly cooked in vacuum-sealed bags in water at low temperature, he discovered that many chefs don't know much about the science behind cooking. He decided to change that with a massive cookbook that was released in March. In 2,438 pages, Modernist Cuisine covers a wide range of cooking techniques and their scientific backgrounds, including heat transfer and the growth of pathogens. (It has recipes, too.)
Announcements & Events

## A New Mathematica Tip Every Day on Twitter

We're excited to announce a new Twitter feed for bite-sized Mathematica hints and tips: Starting today, we're tweeting a new Mathematica tip every day, Monday through Friday. We'll cover everything from Mathematica features and graphics to user interface tips and keyboard shortcuts to miscellaneous fun examples. Follow the new feed on Twitter at @MathematicaTip. Tweet your own favorite hints or questions to us at @MathematicaTip.
Products

## Mathematica Q&A: Four Ways to Sum Integer Digit Blocks

Got questions about Mathematica? The Wolfram Blog has answers! We'll regularly answer selected questions from users around the web. You can submit your question directly to the Q&A Team using this form. This week's question comes from Craig, a hobbyist: For each six-digit number in a list, how can I check whether the sums of the first and last three digits are equal? For example, the sums of the first and last three digits of the number 123,222 are equal because 1 + 2 + 3 == 2 + 2 + 2. There are several different ways of solving this straightforward programming problem in Mathematica, and it's instructive to compare them. In this post you'll see four methods demonstrating various combinations of built-in Mathematica functions for working with lists and digits of integers.