## Acos

### Statement Type

Acos is a mathematical function that operates on REAL arguments.

### Statement Purpose

Acos is Fortran's inverse cosine function. It will return the angle ( in radians ) who's value
of cosine equals the value of the argument passed to it.

### Required Arguments

acos (**x**)

The argument **x** must be of type REAL with value between -1.0 and 1.0. It is the value of
cosine for which the computer will find the corresponding angle of in radians.

### Optional Arguments

There are no optional arguments to this function.

### Results

There are an infinite number of correct answers, so the returned angle is restricted to the
range zero through pi. Just keep in mind that the results that the function returns are in
radians and not degrees. For instance, the next few lines of code will result in the value of
0.7854078 being stored in the variable **angle **not 45.0.

X= 0.7071
angle = acos(x)

If you need angle to be in degrees, you will have to convert using something like the
following.

pi=3.14159265
angle=angle*(180.0/pi)

### For more information and examples see

**lecture** seven**
**

**
**

examples: survey.f

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Written by Jason Wehr : jcw142@psu.edu and Maintained by John Mahaffy :
jhm@cac.psu.edu