Writing to a File in Maple R6

Maple has fprintf statements which work very similar to those of C.

This worksheet illustrates opening a file (potentially one whose

name is computed in a program) and writing some simple text and

numbers to the file.

These first 3 variables specify the location and name of the file being saved.

> DIR_LOCN :=`/tmp`;

DIR_LOCN := `/tmp`

> NUM:= 25;

NUM := 25

> group_suffix := `grp`;

group_suffix := grp

Here || is the string concatenation operator and `` is the empty string.

> group_output_file_path := ``|| DIR_LOCN || `/` || nm || NUM || `.` || group_suffix;

group_output_file_path := `/tmp/nm25.grp`

The format specifications for integers, floats, and algebraic expressions
are illustrated here. Many more exist. Also \t is a tab and \n a newline.

> fd := fopen(group_output_file_path,WRITE);
for i from 1 to 3 do
fprintf(fd,`An integer: %d\n`,i);
fprintf(fd,`\tA float: %g\n`,evalf(log(i+1)));
fprintf(fd,`\t\tAlgebra: %a\n`,expand((x+y)^i));

fd := 1

Especially when debugging it is useful to have your output go to

the current worksheet instead of a file. Setting fd to default does this.

> fd := default;
for i from 1 to 3 do
fprintf(fd,`An integer: %d\n`,i);
fprintf(fd,`\tA Float: %g\n`,evalf(log(i+1)));
fprintf(fd,`\t\tAlgebra: %a\n`,expand((x+y)^i));

fd := default

An integer: 1

	A Float: .693147

		Algebra: x+y

An integer: 2

	A Float: 1.098612

		Algebra: x^2+2*x*y+y^2

An integer: 3

	A Float: 1.386294

		Algebra: x^3+3*x^2*y+3*x*y^2+y^3