III. COMPUTER PROGRAM DOCUMENTATION FOR PROGRAM-GRID 

 1. Program Purpose. 



The purpose of this program is to determine the grid point array 

 in the stretched curvilinear shelf coordinate system and appropriate 

 scale factors needed for program SSURGE. The detailed grid is 

 needed in order for the user to read off depths from an appropriate 

 bathymetric chart of the shelf region at grid locations. 



2. Program Description. 



The program is written in FORTRAN IV language. This program 

 interfaces between Programs CONFORM and SSURGE. It is assumed that 

 the conformal mapping of the storm surge region has been completed 

 to the user's satisfaction. The program GRID takes, in part, as 

 input, the transformation coefficients and determines computing grid 

 information of scale factors, grid point locations, and, at each 

 grid point, the orientation of the C-axis to the x-axis . 



The program GRID is composed of 



MAIN 



Defines constants. Reads transformation coeffi- 

 cients outputed from CONFORM. Reads water 

 depths along a line near center of grid from 

 the seaward boundary to the coast. Computes grid 

 point locations, scale factors (y , v , and F), 

 and, at each grid point, cos and sine 6 . 

 Writes computing grid information. 



SUBROUTINE XUT 



Writes information transferred into XUT. 



SUBROUTINE SHCOR 



SUBROUTINE TRAN 



Determines and writes grid point coordinates in 

 x,y space and the distance in nautical miles 

 between points. 



Computes the x and y coordinates of the trans- 

 form-generated coastline and seaward boundary 

 curve . 



SUBROUTINE TRANl 

 SUBROUTINE TRAN2 



SUBROUTINE CURV9 



Computes x(5,n) and y(5,ri) 



8y/9g^ 



Computes 9x/35 , 3y/85 and 9 = ta.n-'^ [ ■'^ .^z) . 



Contains the expansion curve Y = Z + B(X ) 

 where A , B , and C are constants. The term 

 Y is either Sp (units, nautical miles) or T 

 (units, minutes). The term X ir v^ither S* 

 (units, nautical miles) or T* (uiiits, minutes). 

 This subroutine computes Y and dY/dX given 

 the coefficients and X . 



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