# Physics 203 at Portland State 2014

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digital_sound_project
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digital_sound_project [2014/06/01 20:09]
digital_sound_project [2014/06/04 03:53] (current)
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* This highlights the striking differences in intensity.         * This highlights the striking differences in intensity.
+  -  The other thing is I have been looking at Fourier series calculations and have seen the use of integrals when looking at the Fourier coefficients. Should I be concerned about this?
+    * **Answer**: there are two kinds of Fourier transforms: [[wp>​Fourier transform|continuous]] (liked by theorists) and [[wp>​Discrete Fourier transform|discrete]] (used in numerical computations). The two kinds are closely related, and in the limit of small grid spacing (small dwell time $\Delta t$) they approximately give the same results. But, the continuous transform uses integrals, whereas the discrete one uses simple sums.  You don't need to worry about this too much, just use it as a tool that already works. When you write about it, just say that it decomposes the time-dependent signal into a linear superposition of pure sine and cosine waves at various frequencies on a frequency grid, and gives you the combined amplitude at each frequency, as a function of the point on the frequency grid.
+  - Is there a way to copy and paste the plots from Igor pro into a document or is there another way to display the plots in a document?
+    * **Answer**: You can use
+      * "​screenshots"​ (will work for any screen content, not just IGOR plots) ​
+        * explained in [[white_noise_project#​software_and_data_analysis|the white noise project, Software and data analysis, Item 10]] <- click on the green link
+      * Or, in IGOR, after clicking on your graph, go to the ''​File''​ menu, ''​Save Graphics...''​ submenu, and select ​
+        * the format (PNG or JPEG_
+        * resolution (Other DPI, then 300)
+        * file name -- the name of the picture file that IGOR will create for you
+        * path (home -- will save in the same directory on your computer where you have saved your .pxp experiment
+        * force overwrite -- if you already have that picture file and want to improve it
+      * Then just insert the picture file into your report as picture