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<!--Copyright (C) 1988-2005 by the Institute of Global Environment and Society (IGES). See file COPYRIGHT for more information.-->
<html>
<head>
<title>GrADS Scripting Language Math Functions</title>
</head>
<body text="#000000" bgcolor="e0f0ff">
<h2><b>GrADS Scripting Language Math Functions</b></h2>
<p>
A set of math functions has been developed for use within the GrADS
scripting language. Their use is somewhat self-explanatory, based on
the following descriptions of the arguments and return codes.
<p> <br>
else if (cmpwrd(name,"math_sqrt")) rc = gsfmath(pcmn,8);<br>
else if (cmpwrd(name,"math_abs")) rc = gsfmath(pcmn,9);<br>
<p><code>rc = math_<i>trigfunc</i>(<i>angle <,angle2> </i>)</code>
<ul>
<code><i>trigfunc</i> </code> sin, cos, tan, asin, acos, atan, atan2,
sinh, cosh, tanh, asinh, acosh, or atanh<br>
<code><i>angle</i> </code> must be given in radians
<br>
<code><i>angle2</i> </code> (only used for atan2) <br>
<code>rc </code> the result of
the trig function calculation
</ul>
<p>
<code>rc = math_format(<i>format,num</i>)</code>
<ul>
<code><i>format</i> </code> a C-language style format
statement for a floating point number, e.g. <code>%5.2f</code><br>
<code><i>num</i> </code> the number
to be formatted<br>
<code>rc </code> the formatted
number
</ul>
<code>rc = math_nint(<i>num</i>)</code>
<ul>
<code><i>num</i> </code> a real number
in decimal form<br>
<code>rc </code> <code><i>num</i></code>
rounded up or down to the nearest integer
</ul>
<code>rc = math_int(<i>num</i>)</code>
<ul>
<code><i>num</i> </code> a real number
in decimal form<br>
<code>rc </code> the integer
part of <code><i>num</i></code> not greater than <code><i>num</i></code>
</ul>
<code>rc = math_log(<i>num</i>);</code>
<ul>
<code><i>num</i> </code> any number
> 0<br>
<code>rc </code> natural logarithm
of <code><i>num</i></code>
</ul>
<code></code><code>rc = math_log10(<i>num</i>);</code>
<ul>
<code><i>num</i> </code> any number
> 0.0<br>
<code>rc </code> base 10 logarithm of <code><i>num</i></code>
</ul>
<code></code><code></code><code>rc = math_pow(<i>num,exponent</i>);</code>
<ul>
<p><code><i>num</i> </code> any number<br>
<code><i>exponent</i> </code> any number<br>
<code>rc </code> <code><i>num</i></code>
raised to the power <code><i>exponent</i></code> </p>
</ul>
<p><code>rc = math_sqrt(<i>num</i>)</code> </p>
<ul>
<code><i>num</i> </code> any number<br>
<code>rc </code> the square root
of <code><i>num</i></code>
</ul>
<p><code>rc = math_abs(<i>num</i>)</code> </p>
<ul>
<code><i>num</i> </code> any number<br>
<code>rc </code> the absolute
value of <code><i>num</i></code>
</ul>
<p><code>rc = math_exp(<i>num</i>)</code> </p>
<ul>
<code><i>num</i> </code> any number<br>
<code>rc </code> the result of
the exponential function; <code>e</code> raised to the power <code><i>num</i></code>
</ul>
<code></code><code>rc = math_fmod(<i>num1,num2</i>);</code>
<ul>
<code><i>num1</i> </code> any number<br>
<code><i>num2</i> </code> any number not
equal to zero<br>
<code>rc </code> the remainder
when <code><i>num1</i></code> is divided by <code><i>num2</i></code>
</ul>
<code>rc = math_mod(<i>num1,num2</i>);</code>
<ul>
<code><i>num1</i> </code> any number<br>
<code><i>num2</i> </code> any number not
equal to zero<br>
<code>rc </code> the integer
part of the remainder when <code><i>num1</i></code> is divided by <code><i>num2</i></code>
</ul>
<code>rc = math_strlen(<i>string</i>)</code>
<ul>
<code><i>string</i> </code>
any string variable<br>
<code>rc </code>
the length of <code><i>string</i></code>
</ul>
<code>rc = valnum(<i>string</i>)</code>
<ul>
<code><i>string</i> </code> any string variable<br>
<code>rc 0 - <i>string</i></code>
is not a number<br>
<code> 1 -
<i>string</i></code> is an integer<br>
<code> 2 -
<i>string</i></code> is not an integer
</ul>
<code>rc = wrdpos(<i>string,int</i>)</code>
<ul>
<code><i>string</i> </code>
any string, usually contains more than one word<br>
<code><i>int</i> </code>
an integer<br>
<code>rc </code>
word #<code><i>int</i></code of ><code><i>string</i></code> starts at this character #<br>
</ul>
<p>
<h3>Usage Notes</h3>
<p>
These math functions will only work with GrADS version 1.8 (or higher).
<p>
<h3>Examples </h3>
<p> These script records were taken from a sample script called "<a href="ftp://grads.iges.org/grads/scripts/script_math_demo.gs">script_math_demo.gs</a>".
<p>
<code>
v = 3.1456<br>
fmt = '%-6.1f'<br>
rc = math_format(fmt,v)<br>
say fmt' of 'v' = 'rc<br>
<br>
pi = 3.1415926<br>
d2r = pi/180<br>
angd = 45<br>
ang = angd * d2r<br>
cos = math_cos(ang)<br>
say 'cos of 'angd' = 'cos<br>
<br>
num = '3.1455'<br>
rc = valnum(num)<br>
if (rc = 0) ; say num' is not a number' ; endif<br>
if (rc = 1) ; say num' is an integer' ; endif<br>
if (rc = 2) ; say num' is not an integer' ; endif<br>
<br>
v = 3.0<br>
while(v < 4.0) <br>
rc1 = math_nint(v)<br>
rc2 = math_int(v)<br>
print 'nint of 'v' = 'rc1' int of 'v' = 'rc2<br>
v = v + 0.1<br>
endwhile<br>
<br>
pow = math_pow(2,0.5);<br>
print '2 raised to the power 0.5 = 'pow<br>
<br>
num = math_exp(1)<br>
print 'exp(1) = 'num<br>
<br>
fmod = math_fmod(5,2)<br>
print '5 modulo 2 (the remainder when 5 is divided by 2) = 'fmod<br>
<br>
s = 'this is a test'<br>
rc = math_strlen(s)<br>
print 'length of the string "'s'" = 'rc
p = 2<br>
rc = wrdpos(s,p)<br>
print 'word 'p' of the string "'s'" starts at character 'rc<br>
<br>
</code>
</body>
</html>
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