Scientific Computation Whats the big idea CS 112

Scientific Computation What’s the big idea? CS 112 Scientific Computation Department of Computer Science Wellesley College 1 -

A scientific toolbox ● A computer is a generalpurpose tool for processing information ● Main goal of CS 112 is to learn how to build your own specialized tools for scientific work ● Your tools will be computer programs written in MATLAB Big ideas 2

Data visualization and analysis ● Graphical display of data ● Statistical analysis of data ● Fitting functions to data Big ideas 3

Sunspots ● Discovered independently by Christoph Scheiner (1610) and Galileo (1613) ● Indicate disturbances in the sun’s magnetic field ● The number of sunspots varies over time in a cyclical way ● Sunspot Cycle* discovered by Samuel Schwabe (1843) * There is some connection between sunspots and extreme weather Big ideas 4

The sunspot data: How can we determine the length of the sunspot cycle? Big ideas 5

The length of the sunspot cycle: ~ 12 years Note: virtually no sunspot activity in the years 1650 -1700 (Europe’s mini ice-age) and we’re currently in a low spot in the cycle! Big ideas 6

Visualizing data Big ideas 7

Whodunit? Big ideas 8

Create synthetic data and images simultaneous contrast illusion Perceptual experiments: collect data from human subjects, analyze data, implement and test models of human visual processing Big ideas 9

Ribonucleic acid ● ● ● An RNA molecule is a sequence of nucleotides drawn from Adenine (A), Guanine (G), Cytosine (C), and Uracil (U) Three adjacent nucleotides form a triplet called a codon that corresponds to a single amino acid You’ll write a MATLAB program that translates a sequence of RNA nucleotides to an amino-acid sequence: UANCUAUCUUCCGGUC. . . Tyr Leu Ser Ile Phe Gln Val. . Big ideas 10

Searching databases ● What is the average cholesterol level for women in their twenties who exercise at least 30 minutes a day? cholesterol age sex exercise 189 239 178 185 251 165 . . . 25 35 28 40 28 22 . . . ‘f’ . . . 60 . . . ‘m’ 30 ‘m’ 15 ‘f’ 40 ‘m’ 25 15 Big ideas 11

Designing GUI’s* ● Graphical User Interfaces simplify communication with our programs by using text boxes, pop-up windows, buttons, menus, check boxes, sliders, etc. ● We’ll use MATLAB’s GUI facilities to build our own interactive programs * Pronounced “gooey” Big ideas 12

Physical simulation ● Prof. Yue Hu in Physics, together with students Nicole Du. Rand ‘ 06 and Christina Miller ‘ 08, created animations in MATLAB that simulate simple physical systems ● The Math. Works website has many more examples Big ideas 13

Credits Plotting emissions test data: http: //www. mathworks. com/demos/matlab/. . . analyzing-data-overview-matlab-video-demonstration. html Sunspot data and image: http: //www. macalester. edu/~kaplan http: //web. me. com/uriarte/Earths_Climate/. . . Sunspots_and_solar_cycles_files/sunspot 032901. gif Visualization examples: http: //scv. bu. edu/SCV/vizgal http: //visualizationlab. vassar. edu/instvishome MATLAB Help: Visualizing MRI data http: //www. mathworks. com/products/matlab/demos. html Big ideas 14