Language Issues Misunderstimated? Sublimable? Hopefuller? "I know how hard it is for you to put food on your family.” "I know the human being and fish can coexist peacefully."

Outline Announcements: HW1 due Friday Developing RAD1D Lab

Designing RAD1 Get C0, u, k, dt,t, T, m, L (dx=L/(m-1)) from user Build matrix A using k, dt, dx Build RHS vector f using u, k, and reaction data Solve A*C=b for C t=t+dt If(t<T) Copy C=C0 Change u and k if needed Repeat 2-6 Else d) Output C and quit

Getting Info From User Need several parameter values & a file name Options: Query user? Values in a file & pass file name? Cbasic basic.cmnd I like option 3

Command File m--number of grid points L--length of the domain dt--time step T--end time

Designing Cbasics Get name of command file (user or command line) Read command file and get m, L, dt, T Create a length m array C Fill array with location of grid points Save C to C.txt

Structure of Cbasics Main.c--main program Io.c--functions for input/output ReadComm ReportParams PrintArray System.c--functions for array allocation & error reporting Error newarray_double

Prototypes & Header files C subroutines must declare the types of their inputs and outputs using “prototypes” double sin(double angle_in_radians); void PrintArray(char name[], double C[], int m); Prototypes allow the compiler to check that you are calling a routine in the correct way Suppose subroutine X is implemented in file X.c. In order to call X from another file (Y.c), Y needs to see the prototype for X. Solution--create a header file with the prototype X.c--implements X X.h--prototype for X Both X.c and Y.c must include X.h: #include “X.h” must appear before any call to X or its implementation